I have an exercise of c - c

Question

My exercise is input list integer numbers from keyboard and the end of program by 0. Then print sum of array. This is my code:
#include <stdio.h>
#include <stdlib.h>
const int MAX_ITEMS = 50;
void inputIntegerNumber(int* a, int* count);
int sumOfInteger(int* n, int* count);
int main(int argc, char** argv) {
int x[MAX_ITEMS], count;
inputIntegerNumber(&x, &count);
printf("Sum of array is %d", sumOfInteger(&x, &count));
return (EXIT_SUCCESS);
}
void inputIntegerNumber(int* a, int* count ){
do{
printf("Please! input numbers: ");
scanf("%d", a);
*count++;
}while((*a != 0) && (*count != MAX_ITEMS));
}
int sumOfInteger(int* n, int* count){
int sum = 0;
for (int i = 0; i < *count; i++)
sum += *n;
return sum;
}
I don't know what's wrong with it? It doesn't give me a result same my thinks...

Answer 1

There are some problems like -
inputIntegerNumber(&x, &count);
printf("Sum of array is %d", sumOfInteger(&x, &count));
in both calls you pass &x but x is an array of int and your function expects int * not int (*)[]. This must have given an error atleast.
For both functions you can just pass the array x directly.
And in your function inputIntegerNumber this -
*count++;
You need to increment value of count, so it should be (*count)++. Dereference first and then increment the value.

Answer 2

You are doing some mistakes in your code like passing pointer to a pointer &x value(since array is basically a pointer to some memory location) and overwriting the same location again and again. In scanf("%d", a); you are overwriting the first location again and again without changing a in you input loop.You need to learn about arrays and their usage. In sumOfInteger function also you're not changing the value of n. I changed you code a bit and i was able to see desired output.
#include <stdio.h>
#include <stdlib.h>
const int MAX_ITEMS = 50;
void inputIntegerNumber(int* a, int* count);
int sumOfInteger(int* n, int* count);
int main(int argc, char** argv) {
int x[MAX_ITEMS], count = 0; // zero elements in array
inputIntegerNumber(x, &count);
printf("Sum of array is %d", sumOfInteger(x, &count));
return (EXIT_SUCCESS);
}
void inputIntegerNumber(int* a, int* count ){
int aIndex = 0;
do{
printf("Please! input numbers: ");
scanf("%d", &a[aIndex]);
aIndex++;
}while((a[aIndex-1] != 0) && (aIndex != MAX_ITEMS));
*count = aIndex;
}
int sumOfInteger(int* n, int* count){
int sum = 0;
for (int i = 0; i < *count; i++)
sum += n[i];
return sum;
}
when i run it i can see :
~/Documents/src : $ ./a.out
Please! input numbers: 1
Please! input numbers: 2
Please! input numbers: 3
Please! input numbers: 0
Sum of array is 6

Answer 3

You're overcomplicating things. Before you sit down to write a program, always write the general steps that must be done
Read the numbers from the command line
Convert them to ints and save them in memory
Calculate the sum
Print it
Here is the revised program
#include <stdio.h>
#include <stdlib.h> /* for strtol */
#define DIE(msg) fprintf(stderr, "%s", msg); exit(EXIT_FAILURE)
int main(int argc, char *argv[])
{
int *nums;
if (argc <= 1)
DIE("Usage: [int-list]\n");
/* skip program name */
--argc;
++argv;
nums = malloc(argc * sizeof(int));
if (!nums)
DIE("Out of mem\n");
for (int i = 0; i < argc; ++i) {
char *end;
double val = strtol(argv[i], &end, 0);
if (end == argv[i]) /* no digits detected */
DIE("Usage: [int-list]\n");
nums[i] = val;
}
printf("%d\n", add(nums, argc));
free(nums);
}
int add(int arr[], size_t n)
{
int sum = 0;
for (int i = 0; i < n; ++i)
sum += arr[i];
return sum;
}
To complete the strtol error handling is an exercise for the OP.