strtok函数真是个蹩脚而又恶心的设计（千万不要嵌套使用strtok函数）

       先来看一个程序：

#include <stdio.h>
#include <string.h>

int main()
{
char str[] = "a = 1\nb = 2\nc = 3\nd = 4\ne = 5\nf = 6";

char left[100] = {0};
char right[100] = {0};

char delims[] = "\n";
char *result = strtok(str, delims);
while(result != NULL)
{
printf( "%s\n", result);
sscanf(result, "%s = %s", left, right);
printf( "%s:%s\n", left, right);
result = strtok(NULL, delims);
}

return 0;
}

     程序结果为：

a = 1

a:1

b = 2

b:2

c = 3

c:3

d = 4

d:4

e = 5

e:5

f = 6

f:6

  

    当然，下面这种情况就没法用sscanf来分割了（其实，需要对sscanf函数的返回值进行判断）：

#include <stdio.h>
#include <string.h>

int main()
{
char str[] = "a=1\nb=2\nc=3\nd=4\ne=5\nf=6";

char left[100] = {0};
char right[100] = {0};

char delims[] = "\n";
char *result = strtok(str, delims);
while(result != NULL)
{
printf( "%s\n", result);
sscanf(result, "%s = %s", left, right);
printf( "%s:%s\n", left, right);
result = strtok(NULL, delims);
}

return 0;
}

    所以，要想其他办法来解析，用strtok呗，程序如下：

#include <stdio.h>
#include <string.h>

void splitIntoTwoParts(char *org, char sep, char *left, char *right, int n)
{
char delims[2] = {0};
delims[0] = sep;
char *result = strtok(org, delims);
strncpy(left, result, n - 1);
while(result != NULL)
{
result = strtok(NULL, delims);
strncpy(right, result, n - 1);

return;
}
}

int main()
{
char str[] = "a=1";

char left[100] = {0};
char right[100] = {0};
splitIntoTwoParts(str, '=', left, right, 100);
printf("%s\n", left);
printf("%s\n", right);

return 0;
}

     结果为：

a

1

 

     可见，splitIntoTwoParts函数没什么问题（当然，为了简便起见，我没有考虑异常情况）

     strtok的诡异就在于，下面程序是有问题的：

#include <stdio.h>
#include <string.h>

void splitIntoTwoParts(char *org, char sep, char *left, char *right, int n)
{
char delims[2] = {0};
delims[0] = sep;
char *result = strtok(org, delims);
strncpy(left, result, n - 1);
while(result != NULL)
{
result = strtok(NULL, delims);
strncpy(right, result, n - 1);

return;
}
}

int main()
{
char str[] = "a=1\nb=2\nc=3\nd=4\ne=5\nf=6";

char left[100] = {0};
char right[100] = {0};

char delims[] = "\n";
char *result = strtok(str, delims);
while(result != NULL)
{
printf( "%s\n", result);
splitIntoTwoParts(result, '=', left, right, 100);
printf( "%s:%s\n", left, right);
result = strtok(NULL, delims);
}

return 0;
}

     结果为：

a=1

a:1

    居然没有读到bcdef, 我晕，这个问题花了我1个小时，去百度搜一下就知道，你就明白了，原来，不能嵌套使用strtok函数。strtok好蹩脚啊。上述程序可以改为：

#include <stdio.h>
#include <string.h>

void splitIntoTwoParts(char *org, char sep, char *left, char *right, int n)
{
char delims[2] = {0};
delims[0] = sep;
char *result = strtok(org, delims);
strncpy(left, result, n - 1);
while(result != NULL)
{
result = strtok(NULL, delims);
strncpy(right, result, n - 1);

return;
}
}

int main()
{
char str[] = "a=1\nb=2\nc=3\nd=4\ne=5\nf=6";

char left[100] = {0};
char right[100] = {0};

char delims[] = "\n";
char *result = strtok(str, delims);
char line[20][100] = {0};
int times = 0;

while(result != NULL)
{
printf( "%s\n", result);
strncpy(line[times++], result, 100 - 1);
result = strtok(NULL, delims);
}

int i = 0;
for(i = 0; i < times; i++)
{
splitIntoTwoParts(line[i], '=', left, right, 100);
printf("%s:%s\n", left, right);
}

return 0;
}

     结果为：

a=1

b=2

c=3

d=4

e=5

f=6

a:1

b:2

c:3

d:4

e:5

f:6

        注意，strtok函数还会引起原串的变化，真他妈的蹩脚的设计。