[置顶] Linux C编程--string.h函数解析

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);

看Asic码，str1>str2，返回值 > 0；两串相等，返回0

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;

}

原型：extern char *strstr(char *haystack, char *needle);

所在头文件：#include <string.h>

功能：从字符串haystack中寻找needle第一次出现的位置（不比较结束符NULL)。

说明：返回指向第一次出现needle位置的指针，如果没找到则返回NULL。

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