C code working on online compilers but not on Leetcode

December 4, 2023

So there is a question on Leetcode to make a basic calculator (It just has operators + and -, and ( and ) brackets). For some reason the code is giving incorrect outputs on Leetcode and an online compiler gives correct outputs with the same test cases. What could be the issue here?

My Code(On Leetcode):

int pos = 0;

int calculate(char *s) {
    int sign = 1;
    int sum = 0;
    int len = strlen(s);
    while (pos < len && s[pos] != ')') {
        if (s[pos] == '-') {
            sign = -1;
            printf("-\n");
        }
        else if (s[pos] == '+') {
            sign = 1;
            printf("+\n");
        }
        else if (s[pos] == '(') {
            pos++;
            sum += sign * calculate(s);
            printf("%d\n", sum);
        } else {
            int a = s[pos] - 48;
            if (a >= 0 && a < 10) {
                sum = sum + a * sign;
                printf("%d\n", sum);
            }
        }
        pos++;
    }
    return sum;
}

Code on the Compiler (Added a main function to call the function calculate):

// Online C compiler to run C program online
#include <stdio.h>

int pos = 0;

int calculate(char *s) {
    int sign = 1;
    int sum = 0;
    int len = strlen(s);
    while (pos < len && s[pos] != ')') {
        if (s[pos] == '-') {
            sign = -1;
            printf("-\n");
        }
        else if (s[pos] == '+') {
            sign = 1;
            printf("+\n");
        }
        else if (s[pos] == '(') {
            pos++;
            sum += sign * calculate(s);
            printf("%d\n", sum);
        } else {
            int a = s[pos] - 48;
            if (a >= 0 && a < 10) {
                sum = sum + a * sign;
                printf("%d\n", sum);
            }
        }
        pos++;
    }
    return sum;
}

int main() {
    printf("\n\nResult: %d", calculate(" (2-1 + 2 -(2+2))+8"));
    return 0;
}

Is it an issue with how Leetcode handles global variables?
The testcases used:

Input: s = "1 + 1"
Input: s = " 2-1 + 2 "
Input: s = "(1+(4+5+2)-3)+(6+8)"

In all these testcases, the online compiler gives accurate outputs, whereas Leetcode gave correct output only for the first