Segmentation Fault in C program (using structs)

Question

I keep getting seg fault and I don't know why, if someone could help me with this it would be great. I cannot find the error here............

I get all the print states up till the end of the the first four loop

i however do not get the "out" print statement,, thats where the set fault is

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

void getWords(int arg, char** argWords, Words* words);

void getWords(int arg, char** argWords, Words* words)
{
    printf("In Method\n");

    int ewm=1;
    for(ewm =1 ; ewm<= arg; ewm++){
        int tempr = (strlen(argWords[ewm]) +1);
        printf("tempr: %d\n", tempr);
        words->numWords = words->numWords + tempo;
        printf("numWords: %d\n", words->numWords);
        printf("in\n");
    }


    printf("out\n");
    printf("%d\n", words->numWords);
    int x = 1;
    int y = 0;

    printf("four loop\n");
    for(x= 1; x<=arg; x++){
        printf("SIZE: %d\n", (strlen(argWords[x] )+1));
        char* temp = malloc(strlen(argWords[x])+1);
        printf("%s\n", argWords[x]);
    }
}

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

    if(argc == 0){
        printf("Please input a value/n");
        return 1;
    }

    Words *currWords = malloc(sizeof(Words));
    printf("Mem located\n");

    getWords(argc, argv, currWords);

    return 0;
}

In for(ewm =1 ; ewm<= arg; ewm++){ int tempr = (strlen(argWords[ewm]) +1); printf("tempr: %d\n", tempr); words->numWords = words->numWords + tempo; — what is tempo? Does the code compile? And how is the structure type Words defined? Also, C arrays normally start at index 0, fo you normally use for (ewm = 0; ewm < arg; ewm++) rather than what you wrote. — Jonathan Leffler
– Jonathan Leffler, Commented Sep 18, 2016 at 20:39

Nikita · Accepted Answer · 2016-09-18 18:56:59Z

2

arg is the number of elements in argWords, so the following code from getWords function access out of array bounds:

 for(x= 1; x<=arg; x++)
 {
   printf("SIZE: %d\n", (strlen(argWords[x] )+1));  // <---
   char* temp = malloc(strlen(argWords[x])+1);      // <---

You get unpredictable behavior when accessing argWords[x]. Proper upper bound should be x < arg.

Same problem at:

 for(ewm =1 ; ewm<= arg; ewm++)   // <--- here must be ewm < arg
 {
   int tempr = (strlen(argWords[ewm]) +1)

answered Sep 18, 2016 at 18:56

Nikita

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