How to make a C program to find the interval of a root of an equation

Question

I need help making a C program that calculate the root intervals of a given equation. I made a program based on the concept that if f(a)f(b) < 0, then there exists at least one root in (a, b).

#include <stdio.h>
#include <string.h>
#include <conio.h>
#include <math.h>

#define f(x) x*x + 2*x + 1

void RootInterval(){
    float a[10];
    float b[10];
    float begin, end;
    begin = -50;
    end = -50;
    int count, i = 0;
    while(begin < 50){
        if(f(begin) >= 0){
            while(f(end) >= 0){
                end = end + 1;
            }
            a[i] = begin;
            b[i] = end;
            begin = end + 1;
            i++;
        }
        else {
            while(f(end) < 0){
                end = end + 1;
            }
            a[i] = begin;
            b[i] = end;
            begin = end + 1;
            i++;
        }
    }
    count = sizeof(a) / sizeof(a[0]);
    printf("Root interval is:\n");
    for(i = 0; i < count; i++){
        printf("(%f, %f) ", a[i], b[i]);
    }
     
}

int main(){
    RootInterval();
    return 0;
    
}

But when I run the program, nothing appears on the screen. What am I doing wrong here?

I tried different intervals and different conditions. I was expecting all root intervals in the range of (-50, 50).