Question

Fix the code. Use Valgrind to compile below code with no warning and no memory error. Also give a comment about how you fix the code.

gcc -std=c99 -pedantic -Wall -Wextra -ftrapv -ggdb3 $* -o question5 question5.c && ./question5

gcc -std=c99 -pedantic -Wall -Wextra -ftrapv -ggdb3 -fsanitize=address -o question5 question5.c && ./question5

Both of these should get the same output .

For example if we input

65535

4

3

2

1

it should give us a output with

What is the maximum number of integers you will provide?
Provide your integers (CTRL-D to end):
Sum of integers is: 10

question5.c

#include
#include
#include

// Calculate the sum of a set of integers

/* checkInput: given the result of scanf check if it
* 0 elements read or EOF. If so exit(1) with a warning.
*
*/
void checkInput(int err) {
if (!err || err == EOF) {
printf("\nInvalid input!\n");
exit(1);
}
}

#define N 4
#define MAXINTS 65535
int main() {
int * bufferHeap = (int*)calloc(N, sizeof(int));
size_t numInts = 0;
printf("What is the maximum number of integers you will provide?\n");
checkInput(scanf("%lu", &numInts));
if (numInts > MAXINTS) {
printf("I think that is too many!\n");
exit(1);
}
if (numInts >= N) {
bufferHeap = (int*)realloc(bufferHeap, sizeof(numInts)* numInts);
}
printf("Provide your integers (CTRL-D to end):\n");
for (unsigned int i = 0; i < numInts; i++) {
int newInt = 0;
int ret = scanf("%d", &newInt);
if (!ret) {
printf("\nInvalid input!\n");
exit(1);
}
if (ret == EOF) {
break;
}
bufferHeap[i] = newInt;
}
  
long long int sum = 0;
for (size_t i = 0 ; i < numInts; i++) {
sum += bufferHeap[i];
}
printf("Sum of integers is: %lld\n", sum);
free(bufferHeap);
return 0;
}

Answer 1

//change the value of the numInts when EOF or ctrl+d is pressed as when you use EOF the garbage value is still present in the bufferHeap and hence if the final loop runs for all the elements that we were supposed to input then it gives wrong answer as it adds that garbage value as well and hence if using EOF then change the value of EOF to avoid reading garbage value from the bufferHeap



#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>

// Calculate the sum of a set of integers

/* checkInput: given the result of scanf check if it
* 0 elements read or EOF. If so exit(1) with a warning.
*
*/
void checkInput(int err) {
    if (!err || err == EOF) {
        printf("\nInvalid input!\n");
        exit(1);
    }
}

#define N 4
#define MAXINTS 65535

int main() {
    int *bufferHeap = (int *) calloc(N, sizeof(int));
    size_t numInts = 0;
    printf("What is the maximum number of integers you will provide?\n");
    checkInput(scanf("%lu", &numInts));
    if (numInts > MAXINTS) {
        printf("I think that is too many!\n");
        exit(1);
    }
    if (numInts >= N) {
        bufferHeap = (int *) realloc(bufferHeap, sizeof(numInts) * numInts);
    }
    printf("Provide your integers (CTRL-D to end):\n");
    for (unsigned int i = 0; i < numInts; i++) {
        int newInt = 0;
        int ret = scanf("%d", &newInt);
        if (!ret) {
            printf("\nInvalid input!\n");
            exit(1);
        }
        if (ret == EOF) {
            numInts = i;
            break;
        }
        bufferHeap[i] = newInt;
    }

    long long int sum = 0;
    for (size_t i = 0; i < numInts; i++) {
        sum += bufferHeap[i];
    }
    printf("Sum of integers is: %lld\n", sum);
    free(bufferHeap);
    return 0;
}