C语言函数大全--f开头的函数（下）

#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;
}