常用字符串函数

C语言字符串函数大全

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: 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: 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: 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: 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: 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;

}