-
函数定义
#include <string.h> char *strsep(char **stringp, const char *delim);
stringp是二级指针,即目标字符串首字符地址的地址。
delim是分割符,因为是字符串格式的,函数会把字符串里的每隔字符都当做分割符号。
2. 函数调用
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#include <string.h> |
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#include <stdio.h> |
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int main( int argc, char * argv[]) |
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{ |
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char buf[] = "zhang-guang-rong,jet-li" ; |
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char *src = strdup(buf); |
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|
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char delim[] = "-," ; |
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|
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char * token; |
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for (token=strsep(&src, delim); token!=NULL; token=strsep(&src, delim)){ |
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printf ( "%s\n" , token); |
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} |
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|
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free (src); |
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return 0; |
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} |
输出:
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zhang |
2 |
guang |
3 |
rong |
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jet |
5 |
li |
3. 函数解析
以上述为例,strsep以src="zhang-guang-rong,jet-li"为源字符串。
char* begin = *stringp;
找到第一个包含在delim="-,"的分割符,即zhang后面的'-'。由char *end指向它。
end指向的分隔符重写为'\0'。 # *end='\0'。
然后修改*stringp的指向为end+1,即"guang-rong,jet-li"。
函数返回begin。
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/** Copyright (C) 1992, 93, 96, 97, 98, 99, 2004 Free Software Foundation, Inc. |
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This file is part of the GNU C Library. |
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The GNU C Library is free software; you can redistribute it and/or |
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modify it under the terms of the GNU Lesser General Public |
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License as published by the Free Software Foundation; either |
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version 2.1 of the License, or (at your option) any later version. |
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The GNU C Library is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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Lesser General Public License for more details. |
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You should have received a copy of the GNU Lesser General Public |
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License along with the GNU C Library; if not, write to the Free |
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
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02111-1307 USA. */ |
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#include <string.h> |
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#undef __strsep |
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#undef strsep |
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char * |
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__strsep ( char **stringp, const char *delim) |
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{ |
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char *begin, *end; |
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begin = *stringp; |
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if (begin == NULL) |
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return NULL; |
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/** A frequent case is when the delimiter string contains only one |
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character. Here we don't need to call the expensive `strpbrk' |
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function and instead work using `strchr'. */ |
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if (delim[0] == '\0' || delim[1] == '\0' ) |
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{ |
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char ch = delim[0]; |
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if (ch == '\0' ) |
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end = NULL; |
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else |
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{ |
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if (*begin == ch) |
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end = begin; |
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else if (*begin == '\0' ) |
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end = NULL; |
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else |
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end = strchr (begin + 1, ch); |
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} |
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} |
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else |
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/** Find the end of the token. */ |
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end = strpbrk (begin, delim); |
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if (end) |
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{ |
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/** Terminate the token and set *STRINGP past NUL character. */ |
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*end++ = '\0' ; |
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*stringp = end; |
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} |
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else |
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/** No more delimiters; this is the last token. */ |
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*stringp = NULL; |
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return begin; |
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} |
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weak_alias (__strsep, strsep) |
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strong_alias (__strsep, __strsep_g) |
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libc_hidden_def (__strsep_g) |