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);//注意 ptr-string啊 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);用法：#include <string.h>
功能：比较字符串s1和s2的前n个字符但不区分大小写。
说明：strncmpi是到strnicmp的宏定义
当s1<s2时，返回值<0
当s1=s2时，返回值=0
当s1>s2时，返回值>0
#include <string.h>
#include <stdio.h>int main(void)
{ char *buf1 = "BBB", *buf2 = "bbb"; int ptr;ptr = strcnmpi(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; } 程序例: