函數名: strdup  
功  能: 將串拷貝到新建的位置處  
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;  
 }  
   
   
   

函數名: stricmp  
功  能: 以大小寫不敏感方式比較兩個串  
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;  
}  
   
   

函數名: strerror  
功  能: 返回指向錯誤信息字符串的指針  
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;  
}  
   
   
   

函數名: strcmpi  
功  能: 將一個串與另一個比較, 不管大小寫  
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;  
}  
   
   
   

函數名: strncmp  
功  能: 串比較  
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);  
}  
   
   

函數名: strncmpi  
功  能: 把串中的一部分與另一串中的一部分比較, 不管大小寫  
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;  
}  
   
   

函數名: strncpy  
功  能: 串拷貝  
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;  
}  
   
   

函數名: strnicmp  
功  能: 不注重大小寫地比較兩個串  
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;  
}  
   
   
   

函數名: strnset  
功  能: 將一個串中的所有字符都設為指定字符  
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;  
}  
   
   

函數名: strpbrk  
功  能: 在串中查找給定字符集中的字符  
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;  
}  
   
   
   

函數名: strrchr  
功  能: 在串中查找指定字符的最后一個出現  
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;  
}  
   
   
   

函數名: strrev  
功  能: 串倒轉  
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;  
}  
   

函數名: strset  
功  能: 將一個串中的所有字符都設為指定字符  
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;  
}  
   
   
   

函數名: strspn  
功  能: 在串中查找指定字符集的子集的第一次出現  
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;  
}  
   
   

函數名: strstr  
功  能: 在串中查找指定字符串的第一次出現  
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;  
}  
   
   

函數名: strtod  
功  能: 將字符串轉換為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;  
}  
   
   
   

函數名: strtok  
功  能: 查找由在第二個串中指定的分界符分隔開的單詞  
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;  
}  
   
   
   

函數名: strtol  
功  能: 將串轉換為長整數  
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;  
}  
   

函數名: strupr  
功  能: 將串中的小寫字母轉換為大寫字母  
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;  
}  
   
   
   

函數名: swab  
功  能: 交換字節  
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;  
}  
   
   
   

函數名: system  
功  能: 發出一個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;  
}