c语言函数大全

墙角野猫

函数名: srand
功 能: 初始化随机数发生器
用 法: void srand(unsigned seed);
程序例:
#include
#include
#include
int main(void)
{
int i;
time_t t;
srand((unsigned) time(&t));
printf("Ten random numbers from 0 to 99
");
for(i=0; i<10; i++)
printf("%d
", rand() % 100);
return 0;
}

墙角野猫

函数名: sscanf
功 能: 执行从字符串中的格式化输入
用 法: int sscanf(char *string, char *format[,argument,...]);
程序例:
#include
#include
int main(void)
{
char label[20];
char name[20];
int entries = 0;
int loop, age;
double salary;
struct Entry_struct
{
char name[20];
int age;
float salary;
} entry[20];
/* Input a label as a string of characters restricting to 20 characters */
printf("
Please enter a label for the chart: ");
scanf("%20s", label);
fflush(stdin); /* flush the input stream in case of bad input */
/* Input number of entries as an integer */
printf("How many entries will there be? (less than 20) ");
scanf("%d", &entries);
fflush(stdin); /* flush the input stream in case of bad input */
/* input a name restricting input to only letters upper or lower case */
for (loop=0;loop {
printf("Entry %d
", loop);
printf(" Name : ");
scanf("%[A-Za-z]", entry[loop].name);
fflush(stdin); /* flush the input stream in case of bad input */
/* input an age as an integer */
printf(" Age : ");
scanf("%d", &entry[loop].age);
fflush(stdin); /* flush the input stream in case of bad input */
/* input a salary as a float */
printf(" Salary : ");
scanf("%f", &entry[loop].salary);
fflush(stdin); /* flush the input stream in case of bad input */
}
/* Input a name, age and salary as a string, integer, and double */
printf("
Please enter your name, age and salary
");
scanf("%20s %d %lf", name, &age, &salary);

/* Print out the data that was input */
printf("
Table %s
",label);
printf("Compiled by %s age %d $%15.2lf
", name, age, salary);
printf("-----------------------------------------------------
");
for (loop=0;loop printf("%4d | %-20s | %5d | %15.2lf
",
loop + 1,
entry[loop].name,
entry[loop].age,
entry[loop].salary);
printf("-----------------------------------------------------
");
return 0;
}

墙角野猫

函数名: stat
功 能: 读取打开文件信息
用 法: int stat(char *pathname, struct stat *buff);
程序例:
#include
#include
#include
#define FILENAME "TEST.$$$"
int main(void)
{
struct stat statbuf;
FILE *stream;
/* open a file for update */
if ((stream = fopen(FILENAME, "w+")) == NULL)
{
fprintf(stderr, "Cannot open output file.
");
return(1);
}
/* get information about the file */
stat(FILENAME, &statbuf);
fclose(stream);
/* display the information returned */
if (statbuf.st_mode & S_IFCHR)
printf("Handle refers to a device.
");
if (statbuf.st_mode & S_IFREG)
printf("Handle refers to an ordinary file.
");
if (statbuf.st_mode & S_IREAD)
printf("User has read permission on file.
");
if (statbuf.st_mode & S_IWRITE)
printf("User has write permission on file.
");
printf("Drive letter of file: %c
", &#39;A&#39;+statbuf.st_dev);
printf("Size of file in bytes: %ld
", statbuf.st_size);
printf("Time file last opened: %s
", ctime(&statbuf.st_ctime));
return 0;
}

墙角野猫

函数名: _status87
功 能: 取浮点状态
用 法: unsigned int _status87(void);
程序例:
#include
#include
int main(void)
{
float x;
double y = 1.5e-100;
printf("Status 87 before error: %x
", _status87());
x = y; /* <-- force an error to occur */
y = x;
printf("Status 87 after error : %x
", _status87());
return 0;
}

墙角野猫

函数名: stime
功 能: 设置时间
用 法: int stime(long *tp);
程序例:
#include
#include
#include
int main(void)
{
time_t t;
struct tm *area;
t = time(NULL);
area = localtime(&t);
printf("Number of seconds since 1/1/1970 is: %ld
", t);
printf("Local time is: %s", asctime(area));
t++;
area = localtime(&t);
printf("Add a second: %s", asctime(area));
t += 60;
area = localtime(&t);
printf("Add a minute: %s", asctime(area));
t += 3600;
area = localtime(&t);
printf("Add an hour: %s", asctime(area));
t += 86400L;
area = localtime(&t);
printf("Add a day: %s", asctime(area));
t += 2592000L;
area = localtime(&t);
printf("Add a month: %s", asctime(area));
t += 31536000L;
area = localtime(&t);
printf("Add a year: %s", asctime(area));
return 0;
}

墙角野猫

函数名: stpcpy
功 能: 拷贝一个字符串到另一个
用 法: char *stpcpy(char *destin, char *source);
程序例:
#include
#include
int main(void)
{
char string[10];
char *str1 = "abcdefghi";
stpcpy(string, str1);
printf("%s
", string);
return 0;
}

墙角野猫

函数名: strcat
功 能: 字符串拼接函数
用 法: char *strcat(char *destin, char *source);
程序例:
#include
#include
int main(void)
{
char destination[25];
char *blank = " ", *c = "C++", *Borland = "Borland";
strcpy(destination, Borland);
strcat(destination, blank);
strcat(destination, c);
printf("%s
", destination);
return 0;
}

墙角野猫

函数名: strchr
功 能: 在一个串中查找给定字符的第一个匹配之处\
用 法: char *strchr(char *str, char c);
程序例:
#include
#include
int main(void)
{
char string[15];
char *ptr, c = &#39;r&#39;;
strcpy(string, "This is a string");
ptr = strchr(string, c);
if (ptr)
printf("The character %c is at position: %d
", c, ptr-string);
else
printf("The character was not found
");
return 0;
}

墙角野猫

函数名: strcmp
功 能: 串比较
用 法: int strcmp(char *str1, char *str2);
程序例:
#include
#include
int main(void)
{
char *buf1 = "aaa", *buf2 = "bbb", *buf3 = "ccc";
int ptr;
ptr = strcmp(buf2, buf1);
if (ptr > 0)
printf("buffer 2 is greater than buffer 1
");
else
printf("buffer 2 is less than buffer 1
");
ptr = strcmp(buf2, buf3);
if (ptr > 0)
printf("buffer 2 is greater than buffer 3
");
else
printf("buffer 2 is less than buffer 3
");
return 0;
}

墙角野猫

函数名: strncmpi
功 能: 将一个串中的一部分与另一个串比较, 不管大小写
用 法: int strncmpi(char *str1, char *str2, unsigned maxlen);
程序例:
#include
#include
int main(void)
{
char *buf1 = "BBB", *buf2 = "bbb";
int ptr;
ptr = strcmpi(buf2, buf1);
if (ptr > 0)
printf("buffer 2 is greater than buffer 1
");
if (ptr < 0)
printf("buffer 2 is less than buffer 1
");
if (ptr == 0)
printf("buffer 2 equals buffer 1
");
return 0;
}