How to edit an array in another function than the main function in c programming?

Question

I'd like to increase each element in the array by one in another function than the main function. Then, I'd like to call this function and print in the main function.

#include <stdio.h>

int function(int array2[5]) {

    int i;
    while(i<4) {
        array2[i]=array2[i]+1;
        i++;
    }

    return array2[5];
}

int main() {
int array[5]={1,2,3,4,5};
int answer;

answer[5]=function(array[5]);

int j;
while(j<4) {
    printf("%d \n",answer[j]);
    j++;
}

return 0;
}

Answer 1

There you go. I suppose this is what you want:

#include <stdio.h>

// Since the array named parameters are scoped only within its function,
// they are apart from your array in the main.
void function(int array[], int len) {
    
    int i = 0;
    while(i<len) {
        array[i]=array[i]+1;
        i++;
    }
}

// Or alternatively you can process the array using a pointer
void functionWithPointer(int *array, int len) {
    
    int i = 0;
    while(i<len) {
        *(array+i) = *(array+i)+1;
        i++;
    }
}

int main() {
    int array[]={1,2,3,4,5};
//  int answer; // Not necessary
    int length = sizeof(array) / sizeof(int); // !!!ATTENTION
    
    function(array, length);
    
    // The array values updated by 1
    printf("Array values after 1st update\n");
    for(int k=0; k<length; k++) {
        printf("%d \n",array[k]);
    }
    
    functionWithPointer(array, length);
    
    // The array values updated by 1 again
    printf("Array values after 2nd update\n");
    int j;
    while(j<length) {
        printf("%d \n",array[j]);
        j++;
    }
    
    return 0;
}

Here is the output:

Array values after 1st update
2 
3 
4 
5 
6 
Array values after 2nd update
3 
4 
5 
6 
7