Thread: Converting string to integer

Code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
void St2Int() {
    char inp[10];
    printf("Input String number\n");
    scanf("%s", inp);
    int *p;
    p = (int *)malloc(strlen(inp));
    p = (int *)(inp);
    int res = *p;
    printf("%d\n", res);
}

I am trying to store the input string value in a char pointer first, then, caste it to an integer pointer and then save it in an integer variable, but I am getting wrong output.
My method is stupid but I am a beginner and curious why this code is not working.

Originally Posted by ssharish2005

it could be as simple as this

Code:

    char str[] = "100";
    int number;

    sscanf( str, "%d", &number );
    printf( "number is - %d\n", number );

I didn't know about sscanf() function.
But my question is, why is the variable res not storing the value p is pointing to, in fact, is p pointing to the input value at all?

Originally Posted by amit_s95

Code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
void St2Int() {
    char inp[10];
    printf("Input String number\n");
    scanf("%s", inp);
    int *p;
    p = (int *)malloc(strlen(inp));
    p = (int *)(inp);
    int res = *p;
    printf("%d\n", res);
}

I am trying to store the input string value in a char pointer first, then, caste it to an integer pointer and then save it in an integer variable, but I am getting wrong output.
My method is stupid but I am a beginner and curious why this code is not working.

I don't know if this is relevant or not but I don't think you even needed to malloc p anyway when all you do is immediately reassign the value of the pointer to a stack-based allocation and then store the value of the bytes there interpreted as an integer in a local variable. This would also create a memory leak that you can't fix because you overwrite the location of the heap allocation.