Question

I’m teaching myself C since my uni seems to be obsessed with java, so im writing a stack implementation of type int (ill worry about making it generic later). I came across an error that makes not sense to me, missing ';' before 'type'. As far as i can tell my syntax is right, if it is not please do tell. Anyways here is my code:

stack.h

typedef struct{
    int *elements;
    int size;
    int capacity;
}Stack;

void newStack(Stack *s);
void delStack(Stack *s);
void pushToStack(Stack *s, int value);
int popFromStack(Stack *s);

stack.c

#include "stack.h"
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>

void newStack(Stack *s){
    s->size = 0;
    s->capacity = 4;
    s->elements = (int*) malloc(4 * sizeof(int));

    assert(s->elements != NULL); // allocation worked?
}

void delStack(Stack *s){
    free(s->elements);
}

void pushToStack(Stack *s, int value){
    if(s->size == s->capacity){
        s->size *= 2;
        s->elements = (int *) realloc(s->elements, s->size * sizeof(int));

        assert(s->elements !=NULL); //reallocation worked?
    }
    s->elements[s->size] = value;
    s->size++;
}

int popFromStack(Stack *s){
    assert(s->size>0);
    s->size --;
    return s->elements[s->size];
}

int main()
{
    Stack s1;
    newStack(&s1);
    int i;
    for(i=0; i<3; i++){
        pushToStack(&s1, i);
        printf("%d ", i);
    }
        printf("\n");
    for(i=0; i<3; i++){
        printf("%d ", popFromStack(&s1));
    }

    delStack(&s1);

    getchar();
    return 0;
}

The error occurs in main, on the int i; line, but if i move the line up the error goes away and the program runs flawlessly. I want to know why.

CAUSES ERROR:

    newStack(&s1);
    int i;

NO ERROR:

    int i;
    newStack(&s1);

PS: just in case it matters.. im using MS Visual Studio 2010

Answer 1

Visual Studio is stuck in a time loop somewhere before 1998, back when the standard mandated that all declarations should be at the beginning of a block.

This was changed in C99, and MS does say it supports the most popular features. Sadly this is not one of them.