在C strtok（）中拆分字符串

Question

I want to split strings received from the terminal input, if they are contained on a buffer. If they are I want to print them.

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

char* fich[5]={"ha","he","hi","ho","hu"};

int main(){

char passaarg[70];
const char space[2]= " ";
char *token;
int i;

while(1){

    read(STDIN_FILENO, passaarg, 70);
    for (i = 0; i < 5; i++){
        if(strncmp(passaarg, fich[i], 2) == 0){
            token = strtok(passaarg, space);
            while(token != NULL){
                printf("%s\n", token);
                token = strtok(NULL, space);
                printf("%s\n", token);
            }
            break;
        }
    }
}
return 0;
}

My output is the following one:

ha he
ha
he

he

Segmentation fault (core dumped)

Answer 1

I suspect your problem is here:

token = strtok(passaarg, space);
while(token != NULL){
    printf("%s\n", token);
    token = strtok(NULL, space);
    printf("%s\n", token);
}

That second printf will cause undefined behavior (likely a crash) when strtok returns NULL , as it will when there are no more tokens in the string. Just remove that line.

Stylistically, I'd use a for loop here:

for(token = strtok(passaarg, space); token != NULL; token = strtok(NULL, space)) {
    printf("%s\n", token);
}

Answer 2

 while(token != NULL){
        printf("%s\n", token);
        token = strtok(NULL, space);
    }

The while loop will fail when the token is NULL . At this time you are trying to print this pointer using your second printf() in the while loop which will lead to undefined behavior.

Get rid of your second printf()