A string is a continuous sequence of characters terminated by '\0', the string terminator character. The length of a string is considered to be the number of characters before the string terminator.
一个字符串的真实长度可以通过函数len=strlen(str)来获得，而sizeof的则是连着最后的'\0'一起统计在内，关于sizeof的使用会有专门的随笔讨论，在这就先不详细谈论了。
|
Purpose |
Functions in string.h |
Functions in wchar.h |
|---|---|---|
|
Find the length of a string. |
strlen( ) |
wcslen( ) |
|
Copy a string. |
strcpy( ), strncpy( ) |
wcscpy( ), wcsncpy( ) |
|
Concatenate strings. |
strcat( ), strncat( ) |
wcscat( ), wcsncat( ) |
|
Compare strings. |
strcmp( ), strncmp( ), strcoll( ) |
wcscmp( ), wcsncmp( ), wcscoll( ) |
|
Transform a string so that a comparison of two transformed strings using strcmp( ) yields the same result as a comparison of the original strings using the locale-sensitive function strcoll( ). |
strxfrm( ) |
wcsxfrm( ) |
|
In a string, find: |
||
|
|
strchr( ), strrchr( ) |
wcschr( ), wcsrchr( ) |
|
|
strstr( ) |
wcsstr( ) |
|
|
strcspn( ), strpbrk( ) |
wcscspn( ), wcspbrk( ) |
|
|
strspn( ) |
wcsspn( ) |
|
Parse a string into tokens |
strtok( ) |
wcstok( ) |
一下是一些函数的例子
http://www.cplusplus.com/reference/clibrary/cstring/strchr/
const char * strchr ( const char * str, int character );
char * strchr ( char * str, int character );
Parameters
- str
- C string.
- character
- Character to be located. It is passed as its int promotion, but it is internally converted back to char.
Return Value
A pointer to the first occurrence of character in str.If the value is not found, the function returns a null pointer.
代码
1 /* strchr example */
2 #include <stdio.h>
3 #include <string.h>
4
5 int main ()
6 {
7 char str[] = "This is a sample string";
8 char * pch;
9 printf ("Looking for the 's' character in \"%s\"...\n",str);
10 pch=strchr(str,'s');
11 while (pch!=NULL)
12 {
13 printf ("found at %d\n",pch-str+1);
14 pch=strchr(pch+1,'s');
15 }
16 return 0;
17 }
代码
1 /* strchr example */
2 #include <stdio.h>
3 #include <string.h>
4
5 int main ()
6 {
7 char str[] = "This is a sample string";
8 char * pch;
9 printf ("Looking for the 's' character in \"%s\"...\n",str);
10 pch=strchr(str,'s');
11 while (pch!=NULL)
12 {
13 printf ("found at %d\n",pch-str+1);
14 pch=strchr(pch+1,'s');
15 }
16 return 0;
17 }
Output:
Looking for the 's' character in "This is a sample string"... found at 4 found at 7 found at 11 found at 18 慢慢整理……先这么多 |
先说点它的使用方法
1.for(int i=0;i<strlen(buf);i++)
if(strchr(Set,buf[i])==NULL) code……
这是用来检测buf中的每个字符是否为是Set中的字符。这个很有用处
2.向刚才举的那个例子，统计某个字符在某个串中出现的次数，或这位置之类的
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