[英]char array split ip with strtok
I'm trying to split a IP address like 127.0.0.1 from a file: 我正在尝试从文件中拆分IP地址(例如127.0.0.1):
using following C code: 使用以下C代码:
pch2 = strtok (ip,".");
printf("\npart 1 ip: %s",pch2);
pch2 = strtok (NULL,".");
printf("\npart 2 ip: %s",pch2);
And IP is a char ip[500], that containt an ip. IP是一个char ip [500],其中包含一个ip。
When printing it prints 127 as part 1 but as part 2 it prints NULL? 在打印时,它作为第1部分打印127,但作为第2部分打印NULL?
Can someone help me? 有人能帮我吗?
EDIT: 编辑:
Whole function: 整个功能:
FILE *file = fopen ("host.txt", "r");
char * pch;
char * pch2;
char ip[BUFFSIZE];
IPPart result;
if (file != NULL)
{
char line [BUFFSIZE];
while(fgets(line,sizeof line,file) != NULL)
{
if(line[0] != '#')
{
pch = strtok (line," ");
printf ("%s\n",pch);
strncpy(ip, pch, strlen(pch)-1);
ip[sizeof(pch)-1] = '\0';
//pch = strtok (line, " ");
pch = strtok (NULL," ");
printf("%s",pch);
pch2 = strtok (ip,".");
printf("\nDeel 1 ip: %s",pch2);
pch2 = strtok (NULL,".");
printf("\nDeel 2 ip: %s",pch2);
pch2 = strtok(NULL,".");
printf("\nDeel 3 ip: %s",pch2);
pch2 = strtok(NULL,".");
printf("\nDeel 4 ip: %s",pch2);
}
}
fclose(file);
}
You do a 你做一个
strncpy(ip, pch, sizeof(pch) - 1);
ip[sizeof(pch)-1] = '\0';
This should be 这应该是
strncpy(ip, pch, strlen(pch));
ip[strlen(pch)] = '\0';
or better yet, just 或者更好,只是
strcpy(ip, pch);
because sizeof(pch) - 1
is sizeof(char*) - 1
, which is just 3 bytes on a 32 bit machine. 因为
sizeof(pch) - 1
是sizeof(char*) - 1
,在32位计算机上只有3个字节。 This corresponds to 3 chars, namely "127", which is in line with your observation the second strtok()
giving NULL. 这对应于3个字符,即“ 127”,这与您观察到的第二个
strtok()
给出NULL一致。
I used your code as following and it works for me 我使用您的代码如下,它对我有用
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char ip[500] = "127.0.0.1";
int main() {
char *pch2;
pch2 = strtok (ip,".");
printf("\npart 1 ip: %s",pch2);
pch2 = strtok (NULL,".");
printf("\npart 2 ip: %s",pch2);
return 0;
}
execution 执行
linux$ gcc -o test test.c
linux$ ./test
part 1 ip: 127
part 2 ip: 0
发现了问题,Visual Studio将0添加到指针,多数民众赞成与NULL相同...
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