Question

The following code works fine in ideone but it gives a runtime error in codeblocks IDE . Is my IDE broken or is there any programming language specific issues .

#include<stdio.h>

int main(){
    int *pointer;
    int num = 45;
    *pointer = num;
    printf("pointer points to value %d", *pointer);
    return 0;
}

Answer 1

replace this

*pointer = num;

by

pointer = #

Your pointer should be pointed to a memory space before assignment of value to it.

When you define pointer in this way:

int *pointer;

This meas that you have defined pointer but the pointer is not yet pointing to a memory space. And if you use the pointer directly without pointing it to a memory space (like you did in your code) then you will get undefined behaviour.

pointing the pointer to amemory space could be done by one of the following way:

1) pointing to a static memory

int num;
int *pointer = #

num is an int defined as a static. So the pointer could be pointed to the num memory

2) pointing to a dynamic memory

int *pointer = malloc(sizeof(int));

the pointer could be pointed to a dynamic memory. the dynamic memory could be allocated with malloc() and when the memory became useless we can free memory with free(pointer)