C语言函数大全--t 开头的函数

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

int main() 
{
    double x = 45.0;
    double tan_value = tan(x * M_PI / 180.0);
    printf("The tangent of %lf degrees is %lf\n", x, tan_value);

    float xf = 60.0f;
    float tan_valuef = tanf(xf * M_PI / 180.0f);
    printf("The tangent of %f degrees is %f\n", xf, tan_valuef);

    long double xL = 30.0l;
    long double tan_valueL = tanl(xL * M_PI / 180.0l);
    printf("The tangent of %Lf degrees is %Lf\n", xL, tan_valueL);
    return 0;
}

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

int main() 
{
    double x = 1.0;
    double tan_value = tanh(x);
    printf("%lf 的双曲正切值是 %lf\n", x, tan_value);

    float y = 2.0f;
    float tanh_value = tanhf(y);
    printf("%f 的双曲正切值是 %f\n", y, tanh_value);

    long double z = 3.0l;
    long double tanhl_value = tanhl(z);
    printf("%Lf 的双曲正切值是 %Lf\n", z, tanhl_value);

    return 0;
}

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>

int main() 
{
    char buf[100];
    int fd = open("test.txt", O_RDONLY);
    off_t offset = tell(fd);
    printf("当前的文件偏移量是 %ld\n", offset);

    int nread = read(fd, buf, sizeof(buf));
    offset = tell(fd);
    printf("读取了 %d 个字节后，文件偏移量是 %ld\n", nread, offset);

    close(fd);
    return 0;
}

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>

int main() 
{
    char buf[100];
    int fd = open("test.txt", O_RDONLY);
    off_t offset = lseek(fd, 0, SEEK_CUR);
    printf("当前的文件偏移量是 %ld\n", offset);

    int nread = read(fd, buf, sizeof(buf));
    offset = lseek(fd, 0, SEEK_CUR);
    printf("读取了 %d 个字节后，文件偏移量是 %ld\n", nread, offset);

    close(fd);
    return 0;
}

#include <stdio.h>
#include <dirent.h>

int main() 
{
    DIR *dirp;
    struct dirent *direntp;

    // 打开当前工作目录
    dirp = opendir(".");

    if (dirp == NULL) 
    {
        printf("无法打开目录。\n");
        return 1;
    }

    // 遍历目录下的所有文件和子目录
    while ((direntp = readdir(dirp)) != NULL) 
    {
        printf("%s\n", direntp->d_name);
    }

    closedir(dirp);

    return 0;
}

#include <graphics.h>

int main() {
   initwindow(640, 480, "Example");
   char str[] = "Hello, world!";
   int height = textheight(str); // 当前文本模式下字符的高度
   int width = textwidth(str); // 当前文本模式下字符的宽度
   outtextxy(100, 100, str);
   outtextxy(100, 120, "Height: ");
   outtextxy(170, 120, itoa(height, str, 10));
   outtextxy(100, 140, "Width: ");
   outtextxy(170, 140, itoa(width, str, 10));
   getch();
   closegraph();
   return 0;
}

#include <stdio.h>
#include <time.h>

int main() 
{
    time_t curtime;
    time(&curtime);
    printf("当前时间是 %s", ctime(&curtime));
    return 0;
}

#include <stdio.h>

int main() 
{
    FILE *fp;
    char str[60];

    fp = tmpfile();
    if (fp == NULL) 
    {
        perror("打开临时文件失败");
        return 1;
    }

    fputs("这是一个临时文件", fp);
    rewind(fp);
    fgets(str, sizeof(str), fp);
    printf("从临时文件读取的内容是： %s", str);

    fclose(fp);
    return 0;
}

#include <stdio.h>

int main() 
{
    char tmpname[L_tmpnam];
    char *filename;

    filename = tmpnam(tmpname);
    printf("临时文件名是：%s\n", filename);

    return 0;
}

#include <stdio.h>
#include <ctype.h>

int main() 
{
    char ch = 'A';

    // 将字符转换为其对应的 ASCII 码值
    int ascii_val = toascii(ch);

    printf("字符 %c 的 ASCII 码值为 %d\n", ch, ascii_val);

    return 0;
}

#include <stdio.h>
#include <ctype.h>

int main() 
{
    char str[] = "Hello, World!";
    int i = 0;

    printf("转换前字符串： %s\n", str);

    printf("转换后字符串： ");
    while (str[i]) {
        putchar(tolower(str[i]));
        i++;
    }

    return 0;
}

#include <stdio.h>
#include <ctype.h>

int main() 
{
    char str[] = "Hello, World!";
    int i = 0;

    printf("转换前字符串： %s\n", str);

    printf("转换后字符串： ");
    while (str[i]) {
        putchar(toupper(str[i]));
        i++;
    }

    return 0;
}

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

int main() 
{
    double x = 3.14159;
    float y = 2.71828f;
    long double z = 1.41421356L;

    // 截去 double 类型浮点数的小数部分
    double a = trunc(x);

    // 截去 float 类型浮点数的小数部分
    float b = truncf(y);

    // 截去 long double 类型浮点数的小数部分
    long double c = truncl(z);

    printf("double 类型 %.5lf 的整数部分为 %.0lf\n", x, a);
    printf("float 类型 %.5f 的整数部分为 %.0f\n", y, b);
    printf("long double 类型 %.8Lf 的整数部分为 %.0Lf\n", z, c);

    return 0;
}

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

#define _XOPEN_SOURCE 700

int main() 
{
    time_t rawtime;
    struct tm *timeinfo;

    // 设置时区为 UTC
    setenv("TZ", "UTC", 1);
    tzset();

    time(&rawtime);
    timeinfo = localtime(&rawtime);
    printf("当前时间是：%s", asctime(timeinfo));

    return 0;
}

#include <stdio.h>
#include <windows.h>
#include <time.h>

int main()
{
    time_t rawtime;
    struct tm *timeinfo;

    TIME_ZONE_INFORMATION tzinfo;
    GetTimeZoneInformation(&tzinfo);

    // 将 WCHAR* 转换为 char*
    int len = WideCharToMultiByte(CP_UTF8, 0, tzinfo.StandardName, -1, NULL, 0, NULL, NULL);
    char* standard_name = (char*) malloc(len * sizeof(char));
    WideCharToMultiByte(CP_UTF8, 0, tzinfo.StandardName, -1, standard_name, len, NULL, NULL);

    _putenv_s("TZ", standard_name);
    tzset();

    time(&rawtime);
    timeinfo = localtime(&rawtime);
    printf("当前时间是：%s", asctime(timeinfo));

    free(standard_name);
    return 0;
}

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

int main() 
{
    double x = 5.0;
    float y = 7.2f;
    long double z = 2.5L;

    double result1 = tgamma(x);
    float result2 = tgammaf(y);
    long double result3 = tgammal(z);

    printf("tgamma(%lf) = %lf\n", x, result1);
    printf("tgammaf(%f) = %f\n", y, result2); 
    printf("tgammal(%Lf) = %Lf\n", z, result3);

    return 0;
}