Why am I getting a segmentation fault when iterating over an array?

Asked Dec 31 '19 at 08:22

Active Dec 31 '19 at 08:25

Viewed 92 times

I extracted the function in question from my main project and simplified it in order to demonstrate the problem I have:

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

void read_input(unsigned char **buff, unsigned int *length){

    unsigned int buff_size = 36;
    *buff = (unsigned char *) malloc(buff_size);
    memset(*buff, 0, buff_size);
    unsigned char chr;
    while((chr=getchar()) != '\n' && chr != EOF){
        *buff[*length] = chr;
        printf("%c\n", *buff[*length]);
        ++(*length);

    }
}

int main(int argc, char **argv){

    unsigned char *buff;
    unsigned int length = 0;

    read_input(&buff, &length);
    printf("%s, %i\n", buff, length);

}

If I run the program, and type test, the output is:

t

Segmentation fault (core dumped)

Why is this happening and how can I fix it?

edited Dec 31 '19 at 08:25

asked Dec 31 '19 at 08:22

avidlearner

have you tried debugging the program? – Siddharth Dec 31 '19 at 08:25
10

*buff[*length] -> (*buff)[*length] – dragosht Dec 31 '19 at 08:35
1

Note there are standard C functions for reading input see e.g. https://stackoverflow.com/questions/15883568/reading-from-stdin – stijn Dec 31 '19 at 08:38
EOF usually is -1, so your comparison won't work with `unsigned char`. Consider changing `chr` type to `int` and casting it to `unsigned char` when necessary. – Roy Avidan Dec 31 '19 at 09:04

Why am I getting a segmentation fault when iterating over an array?

0 Answers0