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C语言库函数(S类字母)

王朝c/c++·作者佚名  2008-06-01
窄屏简体版  字體: |||超大  

函数名: sound

功 能: 以指定频率打开PC扬声器

用 法: void sound(unsigned frequency);

程序例:

/* Emits a 7-Hz tone for 10 seconds.

Your PC may not be able to emit a 7-Hz tone. */

#include <dos.h>

int main(void)

{

sound(7);

delay(10000);

nosound();

return 0;

}

函数名: spawnl

功 能: 创建并运行子程序

用 法: int spawnl(int mode, char *pathname, char *arg0,

arg1, ... argn, NULL);

程序例:

#include <process.h>

#include <stdio.h>

#include <conio.h>

int main(void)

{

int result;

clrscr();

result = spawnl(P_WAIT, "tcc.exe", NULL);

if (result == -1)

{

perror("Error from spawnl");

exit(1);

}

return 0;

}

函数名: spawnle

功 能: 创建并运行子程序

用 法: int spawnle(int mode, char *pathname, char *arg0,

arg1,..., argn, NULL);

程序例:

/* spawnle() example */

#include <process.h>

#include <stdio.h>

#include <conio.h>

int main(void)

{

int result;

clrscr();

result = spawnle(P_WAIT, "tcc.exe", NULL, NULL);

if (result == -1)

{

perror("Error from spawnle");

exit(1);

}

return 0;

}

函数名: sprintf

功 能: 送格式化输出到字符串中

用 法: int sprintf(char *string, char *farmat [,argument,...]);

程序例:

#include <stdio.h>

#include <math.h>

int main(void)

{

char buffer[80];

sprintf(buffer, "An approximation of Pi is %f\n", M_PI);

puts(buffer);

return 0;

}

函数名: sqrt

功 能: 计算平方根

用 法: double sqrt(double x);

程序例:

#include <math.h>

#include <stdio.h>

int main(void)

{

double x = 4.0, result;

result = sqrt(x);

printf("The square root of %lf is %lf\n", x, result);

return 0;

}

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 <stdlib.h>

#include <stdio.h>

#include <time.h>

int main(void)

{

int i;

time_t t;

srand((unsigned) time(&t));

printf("Ten random numbers from 0 to 99\n\n");

for(i=0; i<10; i++)

printf("%d\n", rand() % 100);

return 0;

}

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 <stdio.h>

#include <conio.h>

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("\n\nPlease 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<entries;++loop)

{

printf("Entry %d\n", 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("\nPlease enter your name, age and salary\n");

scanf("%20s %d %lf", name, &age, &salary);

/* Print out the data that was input */

printf("\n\nTable %s\n",label);

printf("Compiled by %s age %d $%15.2lf\n", name, age, salary);

printf("-----------------------------------------------------\n");

for (loop=0;loop<entries;++loop)

printf("%4d %-20s %5d %15.2lf\n",

loop + 1,

entry[loop].name,

entry[loop].age,

entry[loop].salary);

printf("-----------------------------------------------------\n");

return 0;

}

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 <sys\stat.h>

#include <stdio.h>

#include <time.h>

#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.\n");

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.\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");

printf("Drive letter of file: %c\n", 'A'+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;

}

函数名: _status87

功 能: 取浮点状态

用 法: unsigned int _status87(void);

程序例:

#include <stdio.h>

#include <float.h>

int main(void)

{

float x;

double y = 1.5e-100;

printf("Status 87 before error: %x\n", _status87());

x = y; /* <-- force an error to occur */

y = x;

printf("Status 87 after error : %x\n", _status87());

return 0;

}

函数名: stime

功 能: 设置时间

用 法: int stime(long *tp);

程序例:

#include <stdio.h>

#include <time.h>

#include <dos.h>

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\n", 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;

}

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 <stdio.h>

#include <string.h>

int main(void)

{

char string[10];

char *str1 = "abcdefghi";

stpcpy(string, str1);

printf("%s\n", string);

return 0;

}

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 <string.h>

#include <stdio.h>

int main(void)

{

char destination[25];

char *blank = " ", *c = "C++", *Borland = "Borland";

strcpy(destination, Borland);

strcat(destination, blank);

strcat(destination, c);

printf("%s\n", destination);

return 0;

}

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 <string.h>

#include <stdio.h>

int main(void)

{

char string[15];

char *ptr, c = 'r';

strcpy(string, "This is a string");

ptr = strchr(string, c);

if (ptr)

printf("The character %c is at position: %d\n", c, ptr-string);

else

printf("The character was not found\n");

return 0;

}

函数名: strcmp

功 能: 串比较

用 法: int strcmp(char *str1, char *str2);

程序例:

#include <string.h>

#include <stdio.h>

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\n");

else

printf("buffer 2 is less than buffer 1\n");

ptr = strcmp(buf2, buf3);

if (ptr > 0)

printf("buffer 2 is greater than buffer 3\n");

else

printf("buffer 2 is less than buffer 3\n");

return 0;

}

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 <string.h>

#include <stdio.h>

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\n");

if (ptr < 0)

printf("buffer 2 is less than buffer 1\n");

if (ptr == 0)

printf("buffer 2 equals buffer 1\n");

return 0;

}

函数名: strcpy

功 能: 串拷贝

用 法: char *strcpy(char *str1, char *str2);

程序例:

#include <stdio.h>

#include <string.h>

int main(void)

{

char string[10];

char *str1 = "abcdefghi";

strcpy(string, str1);

printf("%s\n", string);

return 0;

}

函数名: strcspn

功 能: 在串中查找第一个给定字符集内容的段

用 法: int strcspn(char *str1, char *str2);

程序例:

#include <stdio.h>

#include <string.h>

#include <alloc.h>

int main(void)

{

char *string1 = "1234567890";

char *string2 = "747DC8";

int length;

length = strcspn(string1, string2);

printf("Character where strings intersect is at position %d\n", length);

return 0;

}

函数名: strdup

功 能: 将串拷贝到新建的位置处

用 法: char *strdup(char *str);

程序例:

#include <stdio.h>

#include <string.h>

#include <alloc.h>

int main(void)

{

char *dup_str, *string = "abcde";

dup_str = strdup(string);

printf("%s\n", dup_str);

free(dup_str);

return 0;

}

函数名: stricmp

功 能: 以大小写不敏感方式比较两个串

用 法: int stricmp(char *str1, char *str2);

程序例:

#include <string.h>

#include <stdio.h>

int main(void)

{

char *buf1 = "BBB", *buf2 = "bbb";

int ptr;

ptr = stricmp(buf2, buf1);

if (ptr > 0)

printf("buffer 2 is greater than buffer 1\n");

if (ptr < 0)

printf("buffer 2 is less than buffer 1\n");

if (ptr == 0)

printf("buffer 2 equals buffer 1\n");

return 0;

}

函数名: strerror

功 能: 返回指向错误信息字符串的指针

用 法: char *strerror(int errnum);

程序例:

#include <stdio.h>

#include <errno.h>

int main(void)

{

char *buffer;

buffer = strerror(errno);

printf("Error: %s\n", buffer);

return 0;

}

函数名: strcmpi

功 能: 将一个串与另一个比较, 不管大小写

用 法: int strcmpi(char *str1, char *str2);

程序例:

#include <string.h>

#include <stdio.h>

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\n");

if (ptr < 0)

printf("buffer 2 is less than buffer 1\n");

if (ptr == 0)

printf("buffer 2 equals buffer 1\n");

return 0;

}

函数名: strncmp

功 能: 串比较

用 法: int strncmp(char *str1, char *str2, int maxlen);

程序例:

#include <string.h>

#include <stdio.h>

int main(void)

{

char *buf1 = "aaabbb", *buf2 = "bbbccc", *buf3 = "ccc";

int ptr;

ptr = strncmp(buf2,buf1,3);

if (ptr > 0)

printf("buffer 2 is greater than buffer 1\n");

else

printf("buffer 2 is less than buffer 1\n");

ptr = strncmp(buf2,buf3,3);

if (ptr > 0)

printf("buffer 2 is greater than buffer 3\n");

else

printf("buffer 2 is less than buffer 3\n");

return(0);

}

函数名: strncmpi

功 能: 把串中的一部分与另一串中的一部分比较, 不管大小写

用 法: int strncmpi(char *str1, char *str2);

程序例:

#include <string.h>

#include <stdio.h>

int main(void)

{

char *buf1 = "BBBccc", *buf2 = "bbbccc";

int ptr;

ptr = strncmpi(buf2,buf1,3);

if (ptr > 0)

printf("buffer 2 is greater than buffer 1\n");

if (ptr < 0)

printf("buffer 2 is less than buffer 1\n");

if (ptr == 0)

printf("buffer 2 equals buffer 1\n");

return 0;

}

函数名: strncpy

功 能: 串拷贝

用 法: char *strncpy(char *destin, char *source, int maxlen);

程序例:

#include <stdio.h>

#include <string.h>

int main(void)

{

char string[10];

char *str1 = "abcdefghi";

strncpy(string, str1, 3);

string[3] = '\0';

printf("%s\n", string);

return 0;

}

函数名: strnicmp

功 能: 不注重大小写地比较两个串

用 法: int strnicmp(char *str1, char *str2, unsigned maxlen);

程序例:

#include <string.h>

#include <stdio.h>

int main(void)

{

char *buf1 = "BBBccc", *buf2 = "bbbccc";

int ptr;

ptr = strnicmp(buf2, buf1, 3);

if (ptr > 0)

printf("buffer 2 is greater than buffer 1\n");

if (ptr < 0)

printf("buffer 2 is less than buffer 1\n");

if (ptr == 0)

printf("buffer 2 equals buffer 1\n");

return 0;

}

函数名: strnset

功 能: 将一个串中的所有字符都设为指定字符

用 法: char *strnset(char *str, char ch, unsigned n);

程序例:

#include <stdio.h>

#include <string.h>

int main(void)

{

char *string = "abcdefghijklmnopqrstuvwxyz";

char letter = 'x';

printf("string before strnset: %s\n", string);

strnset(string, letter, 13);

printf("string after strnset: %s\n", string);

return 0;

}

函数名: strpbrk

功 能: 在串中查找给定字符集中的字符

用 法: char *strpbrk(char *str1, char *str2);

程序例:

#include <stdio.h>

#include <string.h>

int main(void)

{

char *string1 = "abcdefghijklmnopqrstuvwxyz";

char *string2 = "onm";

char *ptr;

ptr = strpbrk(string1, string2);

if (ptr)

printf("strpbrk found first character: %c\n", *ptr);

else

printf("strpbrk didn't find character in set\n");

return 0;

}

函数名: strrchr

功 能: 在串中查找指定字符的最后一个出现

用 法: char *strrchr(char *str, char c);

程序例:

#include <string.h>

#include <stdio.h>

int main(void)

{

char string[15];

char *ptr, c = 'r';

strcpy(string, "This is a string");

ptr = strrchr(string, c);

if (ptr)

printf("The character %c is at position: %d\n", c, ptr-string);

else

printf("The character was not found\n");

return 0;

}

函数名: strrev

功 能: 串倒转

用 法: char *strrev(char *str);

程序例:

#include <string.h>

#include <stdio.h>

int main(void)

{

char *forward = "string";

printf("Before strrev(): %s\n", forward);

strrev(forward);

printf("After strrev(): %s\n", forward);

return 0;

}

函数名: strset

功 能: 将一个串中的所有字符都设为指定字符

用 法: char *strset(char *str, char c);

程序例:

#include <stdio.h>

#include <string.h>

int main(void)

{

char string[10] = "123456789";

char symbol = 'c';

printf("Before strset(): %s\n", string);

strset(string, symbol);

printf("After strset(): %s\n", string);

return 0;

}

函数名: strspn

功 能: 在串中查找指定字符集的子集的第一次出现

用 法: int strspn(char *str1, char *str2);

程序例:

#include <stdio.h>

#include <string.h>

#include <alloc.h>

int main(void)

{

char *string1 = "1234567890";

char *string2 = "123DC8";

int length;

length = strspn(string1, string2);

printf("Character where strings differ is at position %d\n", length);

return 0;

}

函数名: strstr

功 能: 在串中查找指定字符串的第一次出现

用 法: char *strstr(char *str1, char *str2);

程序例:

#include <stdio.h>

#include <string.h>

int main(void)

{

char *str1 = "Borland International", *str2 = "nation", *ptr;

ptr = strstr(str1, str2);

printf("The substring is: %s\n", ptr);

return 0;

}

函数名: strtod

功 能: 将字符串转换为double型值

用 法: double strtod(char *str, char **endptr);

程序例:

#include <stdio.h>

#include <stdlib.h>

int main(void)

{

char input[80], *endptr;

double value;

printf("Enter a floating point number:");

gets(input);

value = strtod(input, &endptr);

printf("The string is %s the number is %lf\n", input, value);

return 0;

}

函数名: strtok

功 能: 查找由在第二个串中指定的分界符分隔开的单词

用 法: char *strtok(char *str1, char *str2);

程序例:

#include <string.h>

#include <stdio.h>

int main(void)

{

char input[16] = "abc,d";

char *p;

/* strtok places a NULL terminator

in front of the token, if found */

p = strtok(input, ",");

if (p) printf("%s\n", p);

/* A second call to strtok using a NULL

as the first parameter returns a pointer

to the character following the token */

p = strtok(NULL, ",");

if (p) printf("%s\n", p);

return 0;

}

函数名: strtol

功 能: 将串转换为长整数

用 法: long strtol(char *str, char **endptr, int base);

程序例:

#include <stdlib.h>

#include <stdio.h>

int main(void)

{

char *string = "87654321", *endptr;

long lnumber;

/* strtol converts string to long integer */

lnumber = strtol(string, &endptr, 10);

printf("string = %s long = %ld\n", string, lnumber);

return 0;

}

函数名: strupr

功 能: 将串中的小写字母转换为大写字母

用 法: char *strupr(char *str);

程序例:

#include <stdio.h>

#include <string.h>

int main(void)

{

char *string = "abcdefghijklmnopqrstuvwxyz", *ptr;

/* converts string to upper case characters */

ptr = strupr(string);

printf("%s\n", ptr);

return 0;

}

函数名: swab

功 能: 交换字节

用 法: void swab (char *from, char *to, int nbytes);

程序例:

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

char source[15] = "rFna koBlrna d";

char target[15];

int main(void)

{

swab(source, target, strlen(source));

printf("This is target: %s\n", target);

return 0;

}

函数名: system

功 能: 发出一个DOS命令

用 法: int system(char *command);

程序例:

#include <stdlib.h>

#include <stdio.h>

int main(void)

{

printf("About to spawn command.com and run a DOS command\n");

system("dir");

return 0;

}

 
 
 
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