#include <stdlib.h>
#include <stdio.h>

int main(void)
{
   char str[25];
   double num;
   int sig = 5; 

   num = 1.23;
   gcvt(num, sig, str);
   printf("string = %s\n", str);

   num = -456.78912;
   gcvt(num, sig, str);
   printf("string = %s\n", str);

   num = 0.345e5;
   gcvt(num, sig, str);
   printf("string = %s\n", str);

   return(0);
}

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main()
{
    int gdriver = DETECT, gmode, errorcode;
    struct arccoordstype arcinfo;
    int midx, midy;
    int stangle = 45, endangle = 270;
    char sstr[80], estr[80];

    initgraph(&gdriver, &gmode, "");

    errorcode = graphresult();
    if (errorcode != grOk)
    {
      printf("Graphics error: %s\n", grapherrormsg(errorcode));
      printf("Press any key to halt:");
      getch();
      exit(1);
    }

    midx = getmaxx() / 2;
    midy = getmaxy() / 2;

    setcolor(getmaxcolor());
    arc(midx, midy, stangle, endangle, 100);
    // 取最后一次调用arc的坐标
    getarccoords(&arcinfo);

    sprintf(sstr, "*- (%d, %d)", arcinfo.xstart, arcinfo.ystart);
    sprintf(estr, "*- (%d, %d)", arcinfo.xend, arcinfo.yend);

    outtextxy(arcinfo.xstart, arcinfo.ystart, sstr);
    outtextxy(arcinfo.xend, arcinfo.yend, estr);

    getch();
    closegraph();
    return 0;
}

#include <graphics.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
    int gdriver = DETECT, gmode, errorcode;
    int bkcolor, midx, midy;
    char bkname[35];

    initgraph(&gdriver, &gmode, "");

    errorcode = graphresult();
    if (errorcode != grOk)
    {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1);
    }

    midx = getmaxx() / 2;
    midy = getmaxy() / 2;
    setcolor(getmaxcolor());

    settextjustify(CENTER_TEXT, CENTER_TEXT);
    cleardevice();

    for (int i = WHITE; i >= 0; i--)
    {
        setbkcolor(i);
        bkcolor = getbkcolor(); // 获取当前背景颜色
        if (i == WHITE) setcolor(BLACK);
        else setcolor(WHITE);
        itoa(bkcolor, bkname, 10);
        strcat(bkname," is the current background color.");

        outtextxy(midx, midy, bkname);
        getch();
        cleardevice();
    }

    getch();
    closegraph();
    return 0;
}

#include <stdio.h>

int main()
{
    char ch;
    printf("Input a character:");
    ch = getc(stdin);
    printf("The character input was: '%c'\n", ch);
    return 0;
}

#include <stdio.h>

int main(void)
{
   int c;
   while ((c = getchar()) != '\n')
      printf("%c ", c);

   return 0;
}

#include <graphics.h>

int main(void)
{
    int gdriver = DETECT, gmode, errorcode;
    int color, midx, midy;
    char colname[35];

    initgraph(&gdriver, &gmode, "");

    errorcode = graphresult();
    /* an error occurred */
    if (errorcode != grOk)
    {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1);
    }

    midx = getmaxx() / 2;
    midy = getmaxy() / 2;
    setcolor(getmaxcolor());

    settextjustify(CENTER_TEXT, CENTER_TEXT);

    for (int i = WHITE; i > 0; i--)
    {
        color = getcolor();
        itoa(color, colname, 10);
        strcat(colname, " is the current drawing color.");
        outtextxy(midx, midy, colname);
        getch();
        cleardevice();
        setcolor(i - 1);
    }

    getch();
    closegraph();
    return 0;
}

#include <stdio.h>
#include <dir.h>

#define MAXPATH 1000

int main()
{
   char buffer[MAXPATH];
   getcwd(buffer, MAXPATH);
   printf("The current directory is: %s\n", buffer);
   return 0;
}

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
    int gdriver = DETECT, gmode, errorcode;
    int i, midx, midy;;

    struct palettetype far *pal=NULL;

    initgraph(&gdriver, &gmode, "");

    errorcode = graphresult();
    if (errorcode != grOk)
    {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1);
    }

    midx = getmaxx() / 3;
    midy = getmaxy() / 2;
    setcolor(getmaxcolor());
    // 获取调色板定义结构
    pal = getdefaultpalette();

    char buffer[100];
    for (i=BLACK; i<WHITE + 1; i++)
    {
        sprintf(buffer, "colors[%d] = %d", i, pal->colors[i]);
        outtextxy(midx, midy, buffer);
        getch();
        cleardevice();
    }

    getch();
    closegraph();
    return 0;
}

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main(void)
{
    int gdriver = DETECT, gmode, errorcode;
    char *drivername;
    initgraph(&gdriver, &gmode, "");
    errorcode = graphresult();
    if (errorcode != grOk)
    {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1);
    }

    setcolor(getmaxcolor());

    // 当前图形驱动程序名字
    drivername = getdrivername();

    settextjustify(CENTER_TEXT, CENTER_TEXT);

    outtextxy(getmaxx() / 2, getmaxy() / 2, drivername);

    getch();
    closegraph();
    return 0;
}

#include <graphics.h>
#include <stdio.h>

int main(void)
{
    int gdriver = DETECT, gmode, errorcode;
    int maxx, maxy;
    char pattern[8] = {0x00, 0x70, 0x20, 0x27, 0x25, 0x27, 0x04, 0x04};

    initgraph(&gdriver, &gmode, "");

    errorcode = graphresult();
    if (errorcode != grOk)
    {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1);
    }

    maxx = getmaxx();
    maxy = getmaxy();
    setcolor(getmaxcolor());
    // 选择用户定义的填充模式
    setfillpattern(pattern, getmaxcolor());

    bar(0, 0, maxx, maxy);

    getch();
    // 将用户定义的填充模式拷贝到内存中
    getfillpattern(pattern);

    pattern[0] += 1;
    pattern[1] -= 2;
    pattern[2] += 3;
    pattern[3] -= 4;
    pattern[4] += 5;
    pattern[5] -= 6;
    pattern[6] += 7;
    pattern[7] -= 8;
    // 选择用户定义的填充模式
    setfillpattern(pattern, getmaxcolor());

    bar(0, 0, maxx, maxy);

    getch();
    closegraph();
    return 0;
}

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>

// the names of the fill styles supported
char *fname[] = { "EMPTY_FILL",
                  "SOLID_FILL",
                  "LINE_FILL",
                  "LTSLASH_FILL",
                  "SLASH_FILL",
                  "BKSLASH_FILL",
                  "LTBKSLASH_FILL",
                  "HATCH_FILL",
                  "XHATCH_FILL",
                  "INTERLEAVE_FILL",
                  "WIDE_DOT_FILL",
                  "CLOSE_DOT_FILL",
                  "USER_FILL"
        };

int main()
{
   int gdriver = DETECT, gmode, errorcode;
   struct fillsettingstype fillinfo;
   int midx, midy;
   char patstr[40], colstr[40];

   initgraph(&gdriver, &gmode, "");

   errorcode = graphresult();
   if (errorcode != grOk)
   {
      printf("Graphics error: %s\n", grapherrormsg(errorcode));
      printf("Press any key to halt:");
      getch();
      exit(1);
   }

   midx = getmaxx() / 2;
   midy = getmaxy() / 2;

   // 获取有关当前填充模式和填充颜色的信息
   getfillsettings(&fillinfo);

   sprintf(patstr, "%s is the fill style.", fname[fillinfo.pattern]);
   sprintf(colstr, "%d is the fill color.", fillinfo.color);

   settextjustify(CENTER_TEXT, CENTER_TEXT);
   outtextxy(midx, midy, patstr);
   outtextxy(midx, midy+2*textheight("W"), colstr);

   getch();
   closegraph();
   return 0;
}

#include <graphics.h>

int main(void)
{
    int gdriver = DETECT, gmode, errorcode;
    int midx, midy, mode;
    char numname[80], modename[80];

    initgraph(&gdriver, &gmode, "");

    errorcode = graphresult();
    if (errorcode != grOk)
    {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1);
    }

    midx = getmaxx() / 2;
    midy = getmaxy() / 2;

    // 获取当前图形模式
    mode = getgraphmode();
    sprintf(numname, "%d is the current mode number.", mode);
    sprintf(modename, "%s is the current graphics mode", getmodename(mode));

    settextjustify(CENTER_TEXT, CENTER_TEXT);
    outtextxy(midx, midy, numname);
    outtextxy(midx, midy+2*textheight("W"), modename);

    getch();
    closegraph();
    return 0;
}

#include<graphics.h>
int main()
{
    int driver,mode;
    unsigned size;
    void *buf;

    driver=DETECT;
    mode=0; initgraph(&driver,&mode,"");

    setcolor(15);
    rectangle(20,20,200,200);

    setcolor(RED);
    line(20,20,200,200);

    setcolor(GREEN);
    line(20,200,200,20);

    getch();

    size=imagesize(20,20,200,200);
    if(size!=-1)
    {
        buf=malloc(size);
        if(buf)
        {
            getimage(20,20,200,200,buf);
            putimage(100,100, buf,COPY_PUT);
            putimage(300,50, buf,COPY_PUT);
        }
    }
    outtext("press a key");
    getch();
    return 0;
}

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>

// the names of the line styles supported
char *lname[] = { "SOLID_LINE",
                  "DOTTED_LINE",
                  "CENTER_LINE",
                  "DASHED_LINE",
                  "USERBIT_LINE"
                };

int main()
{
    int gdriver = DETECT, gmode, errorcode;
    struct linesettingstype lineinfo;
    int midx, midy;
    char lstyle[80], lpattern[80], lwidth[80];

    initgraph(&gdriver, &gmode, "");
    errorcode = graphresult();
    if (errorcode != grOk)
    {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1);
    }

    midx = getmaxx() / 2;
    midy = getmaxy() / 2;

    // 取当前线型、模式和宽度
    getlinesettings(&lineinfo);

    sprintf(lstyle, "%s is the line style.", lname[lineinfo.linestyle]);
    sprintf(lpattern, "0x%X is the user-defined line pattern.", lineinfo.upattern);
    sprintf(lwidth, "%d is the line thickness.", lineinfo.thickness);

    settextjustify(CENTER_TEXT, CENTER_TEXT);
    outtextxy(midx, midy, lstyle);
    outtextxy(midx, midy+2*textheight("W"), lpattern);
    outtextxy(midx, midy+4*textheight("W"), lwidth);

    getch();
    closegraph();
    return 0;
}

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
    int gdriver = DETECT, gmode, errorcode;
    int midx, midy;
    char colstr[80];

    initgraph(&gdriver, &gmode, "");

    errorcode = graphresult();
    if (errorcode != grOk)
    {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1);
    }

    midx = getmaxx() / 2;
    midy = getmaxy() / 2;

    sprintf(colstr, "This mode supports colors 0~%d", getmaxcolor());

    settextjustify(CENTER_TEXT, CENTER_TEXT);
    outtextxy(midx, midy, colstr);

    getch();
    closegraph();
    return 0;
}

#include <graphics.h>
#include <stdlib.h>
#include <stdio.h>

int main(void)
{
    int gdriver = DETECT, gmode, errorcode;
    int midx, midy;
    char xrange[80], yrange[80];

    initgraph(&gdriver, &gmode, "");

    errorcode = graphresult();
    if (errorcode != grOk)
    {
        printf("Graphics error: %s\n", grapherrormsg(errorcode));
        printf("Press any key to halt:");
        getch();
        exit(1);
    }

    midx = getmaxx() / 2;
    midy = getmaxy() / 2;

    sprintf(xrange, "X values range from 0~%d", getmaxx());
    sprintf(yrange, "Y values range from 0~%d", getmaxy());

    settextjustify(CENTER_TEXT, CENTER_TEXT);
    outtextxy(midx, midy, xrange);
    outtextxy(midx, midy+2*textheight("W"), yrange);

    getch();
    closegraph();
    return 0;
}

#include<stdio.h>
#include<math.h>

int main()
{
    double x = 10.24;
    printf("floor(%.2lf) = %.2lf\n", x, floor(x));

    float xf = 5.63;
    printf("floorf(%.2f) = %.2f\n", xf, floorf(xf));

    long double xL = 2.89;
    printf("floorl(%.2Lf) = %.2Lf\n", xL, floorl(xL));
    return 0;
}

#include <stdio.h>

int main()
{
    FILE *stream = fopen("STU.FIL", "w");
    // 清除所有缓冲区
    // 返回打开的流（输入和输出）的数量
    printf("%d streams were flushed.\n", _flushall());
    fclose(stream);
    return 0;
}

#include <stdio.h>
#include <math.h>

int main() {
    
    double x = 2.0, y = 3.0, z = 4.0;
    float xf = 2.0, yf = 3.0, zf = 4.0;
    long double xL = 2.0, yL = 3.0, zL = 4.0;

    printf("fma(%lf, %lf, %lf) = %lf\n", x, y, z, fma(x, y, z));
    printf("fmaf(%f, %f, %f) = %f\n", xf, yf, zf, fmaf(xf, yf, zf));
    printf("fmal(%Lf, %Lf, %Lf) = %Lf\n", xL, yL, zL, fmal(xL, yL, zL));
    
    return 0;
}

#include<stdio.h>
#include<math.h>

int main()
{
    double x = 10.24, y = 5.63;
    printf("fmax(%.2lf, %.2lf) = %.2lf\n", x, y, fmax(x, y));

    float xf = 5.63, yf = 2.89;
    printf("fmaxf(%.2f, %.2f) = %.2f\n", xf, yf, fmaxf(xf, yf));

    long double xL = 2.89, yL = 4.56;
    printf("fmaxl(%.2Lf, %.2Lf) = %.2Lf\n", xL, yL, fmaxl(xL, yL));
    return 0;
}

#include<stdio.h>
#include<math.h>

int main()
{
    double x = 10.24, y = 5.63;
    printf("fmin(%.2lf, %.2lf) = %.2lf\n", x, y, fmin(x, y));

    float xf = 5.63, yf = 2.89;
    printf("fminf(%.2f, %.2f) = %.2f\n", xf, yf, fminf(xf, yf));

    long double xL = 2.89, yL = 4.56;
    printf("fminl(%.2Lf, %.2Lf) = %.2Lf\n", xL, yL, fminl(xL, yL));
    return 0;
}

#include<stdio.h>
#include<math.h>

int main()
{
    double x = 10.24, y = 5.63;
    printf("fmod(%.2lf, %.2lf) = %.20lf\n", x, y, fmod(x, y));

    float xf = 5.63, yf = 2.89;
    printf("fmodf(%.2f, %.2f) = %.20f\n", xf, yf, fmodf(xf, yf));

    long double xL = 2.89, yL = 4.56;
    printf("fmodl(%.2Lf, %.2Lf) = %.20Lf\n", xL, yL, fmodl(xL, yL));
    return 0;
}

#include <string.h>
#include <stdio.h>

int main(void)
{
    FILE *fp;
    char buf[30] = "Hello, Huazie 123456789";
    fp = fopen("STU.FIL", "w");
    printf("temp.txt is created and opened\n");
    fwrite(&buf, strlen(buf), 1, fp);
    printf("temp.txt is writed\n");
    fclose(fp);
    printf("temp.txt is closed");
    return 0;
}

#include <stdio.h>

int main()
{
    FILE *stream;
    stream = fopen("temp.txt", "w");
    fprintf(stream, "%s:%d\n", "Hello Huazie", 456);
    fclose(stream);
    return 0;
}

#include <stdio.h>

int main(void)
{
   char msg[] = "Hello Huazie";
   int i = 0;

   while (msg[i])
   {
      fputc(msg[i], stdout);
      i++;
   }
   return 0;
}

#include <stdio.h>

int main(void)
{
    char msg[] = "This is a test";
    int i = 0;

    while (msg[i])
    {
      fputchar(msg[i]);
      i++;
    }
    return 0;
}

#include <stdio.h>

int main()
{
    int result = fputs("Hello Huazie\n1234", stdout);
    printf("\nresult = %d", result);
    return 0;
}

#include <string.h>
#include <stdio.h>

int main(void)
{
    FILE *stream;
    char msg[20] = "Hello, Huazie";
    char buf[20];

    // 以读写模式打开文件。若文件不存在则创建该文件。若文件存在则其内容将被清除。
    if ((stream = fopen("temp.txt", "w+")) == NULL)
    {
        fprintf(stderr, "Cannot open output file.\n");
        return 1;
    }
    // 向文件流中写入数据
    fwrite(msg, strlen(msg)+1, 1, stream);
    // 重定位流上的文件指针到文件开头
    fseek(stream, SEEK_SET, 0);
    // 从文件流中读取数据
    fread(buf, strlen(msg)+1, 1, stream);
    printf("%s\n", buf);

    fclose(stream);
    return 0;
}

#include <stdio.h>
#include <string.h>
#include <malloc.h>
int main()
{
    char *str;
    str = (char *) malloc(7); 
    strcpy(str, "huazie");
    printf("string = %-10s, Address = %u, len = %d\n", str, str, strlen(str));
    str = (char *) realloc(str,25); //重新分配内存
    strcat(str, ".com");
    printf("string = %-10s, Address = %u, len = %d\n", str, str, strlen(str));
    free(str);// 释放已分配的内存空间
    //内存空间释放后，该空间上的值未知
    printf("string = %-10s, Address = %u, len = %d\n", str, str, strlen(str));
    return 0;
}

#include<stdio.h>
int main()
{
    if(freopen("temp.txt", "w", stdout) == NULL)
        fprintf(stderr,"error redirecting stdout\n");
    printf("Hello, %s", "Huazie");
    fclose(stdout);
    return 0;
}

#include<stdio.h>
#include<math.h>

int main()
{
    int exp;
    double x = 10.24;
    printf("frexp(%.2lf, exp = %d) = %.20lf\n", x, exp, frexp(x, &exp));

    float xf = 5.63;
    printf("frexpf(%.2f, exp = %d) = %.20f\n", xf, exp, frexpf(xf, &exp));

    long double xL = 2.89;
    printf("frexpl(%.2Lf, exp = %d) = %.20Lf\n", xL, exp, frexpl(xL, &exp));
    return 0;
}

#include <stdlib.h>
#include <stdio.h>

int main(void)
{
    int i;
    printf("Input an integer: ");
    if (fscanf(stdin, "%d", &i))
      printf("The integer is: %d\n", i);
    else
    {
      fprintf(stderr, "Error reading an integer from stdin.\n");
      exit(1);
    }
    return 0;
}

#include <stdio.h>

long filesize(FILE *stream);

int main(void)
{
    FILE *stream = fopen("temp.txt", "w+");
    fprintf(stream, "This is a test");
    printf("The size of temp.txt is %ld bytes\n", filesize(stream));
    fclose(stream);
    return 0;
}

long filesize(FILE *stream)
{
    long curpos, length;
    // 文件指针当前位置相对于文件首的偏移字节数
    curpos = ftell(stream);
    // 重定向文件指针到文件尾，偏移量 0
    fseek(stream, 0L, SEEK_END);
    length = ftell(stream);
    return length;
}

#include <stdlib.h>
#include <stdio.h>

void showpos(FILE *stream);

int main(void)
{
    FILE *stream;
    fpos_t filepos;

    stream = fopen("STU.FIL", "w+");
    // 获取当前文件指针的位置
    fgetpos(stream, &filepos);
    fprintf(stream, "This is a test");
    // 展示当前文件指针的位置
    showpos(stream);

    /* set a new file position, display it */
    if (fsetpos(stream, &filepos) == 0)
        showpos(stream);
    else
    {
        fprintf(stderr, "Error setting file pointer.\n");
        exit(1);
    }

    fclose(stream);
    return 0;
}

void showpos(FILE *stream)
{
    fpos_t pos;
    // 展示当前文件指针的位置
    fgetpos(stream, &pos);
    printf("File position: %ld\n", pos);
}

#include <sys\stat.h>
#include <stdio.h>
#include <time.h>

int main()
{
    struct stat statbuf;
    FILE *stream;

    if ((stream = fopen("STU.FIL", "w+")) == NULL)
    {
        fprintf(stderr, "Cannot open output file.\n");
        exit(1);
    }
    fprintf(stream, "This is a test");
    fflush(stream);

    // get information about the file
    fstat(fileno(stream), &statbuf);
    fclose(stream);

    if (statbuf.st_mode & S_IFCHR)
        printf("Handle refers to a device.\n");
    if (statbuf.st_mode & S_IFREG)
        printf("Handle refers to an ordinary file.\n");
    if (statbuf.st_mode & S_IREAD)
        printf("User has read permission on file.\n");
    if (statbuf.st_mode & S_IWRITE)
        printf("User has write permission on file.\n");
    // 不知道为啥，我这里文件的驱动号是空
    printf("Drive letter of file: %c\n", statbuf.st_dev);
    printf("Size of file in bytes: %ld\n", statbuf.st_size);
    printf("Time file last opened: %s\n", ctime(&statbuf.st_ctime));
    return 0;
}

#include <stdio.h>

int main(void)
{
    FILE *stream = fopen("temp.txt", "w+");
    fprintf(stream, "This is a test");
    printf("The file pointer is at byte %ld\n", ftell(stream));
    fclose(stream);
    return 0;
}

#include <stdio.h>

struct mystruct
{
    int i;
    char ch;
};

int main(void)
{
    FILE *stream;
    struct mystruct s;
    // 以只写模式打开或新建一个二进制文件。
    if ((stream = fopen("test.txt", "wb")) == NULL) 
    {
        fprintf(stderr, "Cannot open output file.\n");
        return 1;
    }
    s.i = 0;
    s.ch = 'A';
    fwrite(&s, sizeof(s), 1, stream); 
    fclose(stream); 

    // 以只读模式打开或新建一个二进制文件。
    if ((stream = fopen("test.txt", "rb")) == NULL) 
    {
        fprintf(stderr, "Cannot open output file.\n");
        return 1;
    }
    struct mystruct s1;
    fread(&s1, sizeof(s1), 1, stream);
    printf("%d %c", s1.i, s1.ch);
    fclose(stream);

    return 0;
}

#include <stdio.h>
#include <math.h>

int main(void)
{
    double result, x = -4.5;
    result = fabs(x); // 取绝对值

    float resultf, xf = -3.5;
    resultf = fabsf(xf);

    long double resultL, xL = -2.5;
    resultL = fabsl(xL);

    printf("The absolute value of %lf is %lf\n", x, result);

    printf("The absolute value of %f is %f\n", xf,  resultf);

    printf("The absolute value of %Lf is %Lf\n", xL, resultL);

    return 0;
}

#include <string.h>
#include <stdio.h>

int main(void)
{
    FILE *fp;
    char buf[30] = "Hello, Huazie 123456789";
    fp = fopen("temp.txt", "w");
    printf("temp.txt is created and opened\n");
    fwrite(&buf, strlen(buf), 1, fp);
    printf("temp.txt is writed\n");
    fclose(fp);
    printf("temp.txt is closed");
    return 0;
}

#include <stdio.h>

#define fcloseall() _fcloseall();

int main()
{
    int streams_closed;

    fopen("temp.one", "w");
    fopen("temp.two", "w");

    // 关闭打开流
    streams_closed = fcloseall();

    if (streams_closed == EOF)
        perror("Error");
    else
        printf("%d streams were closed.\n", streams_closed);

    return 0;
}

#include <stdlib.h>
#include <stdio.h>
#include <conio.h>

int main()
{
    char *string;
    double value;
    int decpt, sign;

    int ndigit = 10;
    value = 9.876;
    string = fcvt(value, ndigit, &decpt, &sign);
    printf("string = %-18s decpt = %d sign = %d value = %lf\n", string, decpt, sign, value);

    value = -123.45;
    ndigit= 15;
    string = fcvt(value, ndigit, &decpt, &sign);
    printf("string = %-18s decpt = %d sign = %d value = %lf\n", string, decpt, sign, value);

    value = 0.6789e5; /* 科学记数法 scientific notation */
    ndigit = 5;
    string = fcvt(value, ndigit, &decpt, &sign);
    printf("string = %-18s decpt = %d sign = %d value = %lf\n", string, decpt, sign, value);

    return 0;
}

#include <stdio.h>  
#include <math.h>
  
int main() {  

  double x = 5.000011;
    double y = 3.000041;

    double result_d = fdim(x, y);

    float xf = 5.000011f;
    float yf = 3.000031f;
    float result_f = fdimf(xf, yf);

    long double xLD = 5.000011L;
    long double yLD = 3.000021L;
    long double result_ld = fdiml(xLD, yLD);

    printf("fdim(%.6lf, %.6lf) = %.6lf\n", x, y, result_d);
    printf("fdimf(%.6f, %.6f) = %.6f\n", xf, yf, result_f);
    printf("fdiml(%.6Lf, %Lf) = %.6Lf\n", xLD, yLD, result_ld);
  
    return 0;  
}

#include <sys\stat.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>

int main(void)
{
    int handle;
    FILE *stream;
    // 打开 temp.txt 文件
    handle = open("temp.txt", O_CREAT | O_RDWR, S_IREAD | S_IWRITE);
    // 将文件描述符和文件流关联
    stream = fdopen(handle, "w");

    if (stream == NULL)
        printf("fdopen failed\n");
    else
    {
        fprintf(stream, "%s:%d\n", "Hello world", 123);
        fclose(stream);
    }
    return 0;
}

#include <stdio.h>

int main(void)
{
    FILE *stream;
    // 以读取模式，打开文件 temp.txt
    stream = fopen("temp.txt", "r");

    // 检查是否文件结束【0：未结束 非0：结束】
    while (!feof(stream))
        printf("%c", fgetc(stream));

    fclose(stream);
    return 0;
}

#include <stdio.h>

int main(void)
{
    FILE *stream;
    // 以写模式打开文件STU.FIL
    stream = fopen("STU.FIL", "w");
    // 通过尝试读取来强制出现错误条件
    (void) getc(stream);
    // 检测流上的错误【返回0，表示未出错；返回非零值，表示出错。】
    if (ferror(stream))
    {
        printf("Error reading from STU.FIL\n");
        // 重置错误和EOF标志
        clearerr(stream);
    }
    fclose(stream);
    return 0;
}