這兩個函數都是拆分字符的API，都是線性安全函數，特意寫了個實例對比兩個函數的不通，從MAN手冊中可以看出兩個函數都會改變原有字符串。

strsep() function was introduced as a replacement for strtok(3), since the latter cannot handle empty fields. However, strtok(3) conforms to?C89/C99 and hence is more portable.

也就是說strsep是strtok的替代接口，但可能在移植的時候會出現問題。

#include <stdio.h> #include <string.h> #include <stdlib.h> int main() { char ptr[]={ "abc;defghijk; lmnopqrst ;uvwxyz "}; char *p = ptr, *str= "; "; int i = 0;char *sep = NULL;printf("Original string : %s\n", ptr);while((sep = strsep(&p, str)) != NULL){if(!strcmp(sep, "")){printf("more than %s appear \n", sep);continue;}printf("Line %d: %s\n", ++i, sep); }return 0; } 輸出結果：

TestServer $ ./strsep?
Original string : abc;defghijk; ? ? lmnopqrst ;uvwxyz?
Line 1: abc
Line 2: defghijk
more than ?appear?
more than ?appear?
more than ?appear?
more than ?appear?
more than ?appear?
Line 3: lmnopqrst
more than ?appear?
Line 4: uvwxyz
more than ?appear?

會多次出現空字符串的問題，這是因為strsep在處理多余一個的delimit字符是會返回空字符串代替NULL。

#include <stdio.h> #include <string.h> #include <stdlib.h> int main() { char ptr[]={ "abc;defghijk; lmnopqrst ;uvwxyz "}; char *p = ptr, *dlm= "; "; int i = 0;char *sep = NULL, *saveptr = NULL;printf("Original string : %s\n", ptr);while((sep = strtok_r(p, dlm, &saveptr)) != NULL){printf("Line %d: %s\n", ++i, sep); // note: p have to set NULL, or will not break while();p = NULL;}return 0; }

輸出結果：TestServer$ ./strtok_r Original string : abc;defghijk; lmnopqrst ;uvwxyz?

Line?1: abc

Line?2: defghijk

Line?3: lmnopqrst

Line?4: uvwxyzstrtok?

函數會將多余一個delimit字符轉換成'\0', 注意p =　NULL操作，在第二次調用strtok&strtok_r時需要將str=NULL。

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