C语言字符串操作函数总结
C语言字符串操作函数总结
Part 1: Copying
1、 函数名: strcpy
用 法: char * strcpy ( char * destination, const char * source );
功 能: 串拷贝(Copies the C string pointed by source into the array pointed by destination, including the terminating null character. To avoid overflows, the size of the array pointed by destination shall be long enough to contain the same C string as source (including the terminating null character), and should not overlap in memory with source.)
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;
}
2、函数名: strncpy
用 法: char * strncpy ( char * destination, const char * source, size_t num );
功 能: 指定长度的串拷(Copies the first num characters of source to destination. If the end of the source C string (which is signaled by a null-character) is found before num characters have been copied, destination is padded with zeros until a total of num characters have been written to it. No null-character is implicitly appended to the end of destination, so destination will only be null-terminated if the length of the C string in source is less than num.)
程序例:
#include <stdio.h>
#include <string.h>
int main ()
{
char str1[]= "To be or not to be";
char str2[6];
strncpy (str2,str1,5);
str2[5]='/0';//no '/0' will be appendeded to the end of destination automatically
puts (str2);//输出To be
return 0;
}
另外参考：
void * memcpy ( void * destination, const void * source, size_t num );
void * memmove ( void * destination, const void * source, size_t num );
Part 2: Concatenation
3、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;
}
另外参考：
char * strncat ( char * destination, char * source, size_t num );
Part 3: Comparison
4、函数名: strcmp
功 能: 串比较，大小写敏感
用 法: int strcmp(char *str1, char *str2);
比较ASCII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;
}
4.1、函数名: stricmp（还有一种写法是strcmpi，VC 6.0都支持）
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;
}
5、函数名: strncmp
功 能: 将一个串中的一部分与另一个串比较, 大小写敏感
用 法: int strncmp(char *str1, char *str2, size_t 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;
}
5.1、函数名: strncmpi（还有一种写法是strnicmp，VC 6.0都支持）
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;
}
其它参考：
int memcmp ( const void * ptr1, const void * ptr2, size_t num );
int strcoll ( const char * str1, const char * str2 );
size_t strxfrm ( char * destination, const char * source, size_t num );
Part 4: Searching
6、函数名: strchr
用 法: char *strchr(char *str, char c);
功 能: 在一个串中查找给定字符的第一个匹配之处(Locate first occurrence of character in string, Returns a pointer to the first occurrence of character in the C string str. The terminating null-character is considered part of the C string. Therefore, it can also be located to retrieve a pointer to the end of a string.)
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;
}
7、函数名: strcspn
用 法: int strcspn(char *str1, char *str2);
功 能: 在第一个串中查找包含任何第二个串给定字符集内容的位置(Get span until character in string, Scans str1 for the first occurrence of any of the characters that are part of str2, returning the number of characters of str1 read before this first occurrence. The search includes the terminating null-characters, so the function will return the length of str1 if none of the characters of str2 are found in str1.)
程序例:
#include <stdio.h>
#include <string.h>
#include <alloc.h>
int main(void)
{
char *string1 = "1234567890";
char *string2 = "747D18";
int length;
length = strcspn(string1, string2); //length=0, match letter is 1
printf("Character where strings intersect is at position %d/n", length);
return 0;
}
8、函数名: strspn
用 法: int strspn(char *str1, char *str2);
功 能: 在串中查找指定字符集出现在串的子集的长度(Get span of character set in string, Returns the length of the initial portion of str1 which consists only of characters that are part of str2)
程序例:
#include <stdio.h>
#include <string.h>
#include <alloc.h>
int main(void)
{
char *string1 = "1234567890";
char *string2 = "23DC81";
int length;
length = strspn(string1, string2); //length=3, the initial portion '123' cnsists of characters that are pare of string2
printf("Character where strings differ is at position %d/n", length);
return 0;
}
9、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;
}
将C语言梳理一下，分布在以下10个章节中：
- Linux-C成长之路（一）：Linux下C编程概要 http://www.linuxidc.com/Linux/2014-05/101242.htm
- Linux-C成长之路（二）：基本数据类型 http://www.linuxidc.com/Linux/2014-05/101242p2.htm
- Linux-C成长之路（三）：基本IO函数操作 http://www.linuxidc.com/Linux/2014-05/101242p3.htm
- Linux-C成长之路（四）：运算符 http://www.linuxidc.com/Linux/2014-05/101242p4.htm
- Linux-C成长之路（五）：控制流 http://www.linuxidc.com/Linux/2014-05/101242p5.htm
- Linux-C成长之路（六）：函数要义 http://www.linuxidc.com/Linux/2014-05/101242p6.htm
- Linux-C成长之路（七）：数组与指针 http://www.linuxidc.com/Linux/2014-05/101242p7.htm
- Linux-C成长之路（八）：存储类，动态内存 http://www.linuxidc.com/Linux/2014-05/101242p8.htm
- Linux-C成长之路（九）：复合数据类型 http://www.linuxidc.com/Linux/2014-05/101242p9.htm
- Linux-C成长之路（十）：其他高级议题