can't communicate with pipes between 2 different c programs

Question

I Have these 2 programs:

nicecmp.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int main() {
    int pipe_to_loop[2];  // Pipe for sending data to loopcmp.c
    int pipe_from_loop[2];  // Pipe for receiving data from loopcmp.c

    // Create the pipes
    if (pipe(pipe_to_loop) == -1 || pipe(pipe_from_loop) == -1) {
        perror("Pipe creation failed");
        return 1;
    }

    // Fork to create a child process for loopcmp.c
    pid_t pid = fork();

    if (pid < 0) {
        perror("Fork failed");
        return 1;
    } else if (pid == 0) {
        // Child process - loopcmp.c
        // Close unused pipe ends
        close(pipe_to_loop[1]);
        close(pipe_from_loop[0]);

        // Duplicate the read end of pipe_to_loop to stdin (file descriptor 0)
        dup2(pipe_to_loop[0], 0);

        // Duplicate the write end of pipe_from_loop to stdout (file descriptor 1)
        dup2(pipe_from_loop[1], 1);

        // Execute loopcmp.c
        execlp("./loopcmp", "./loopcmp", NULL);

        perror("Exec failed");
        return 1;
    } else {
        // Parent process - nicecmp.c
        // Close unused pipe ends
        close(pipe_to_loop[0]);
        close(pipe_from_loop[1]);

        // Data to be sent to loopcmp.c
        const char *str1 = "Hello";
        const char *str2 = "World";
        int number = 42;

        // Send data to loopcmp.c through the pipe
        write(pipe_to_loop[1], str1, strlen(str1) + 1);
        write(pipe_to_loop[1], str2, strlen(str2) + 1);
        write(pipe_to_loop[1], &number, sizeof(int));

        // Read data back from loopcmp.c
        int result;
        read(pipe_from_loop[0], &result, sizeof(int));

        // Print the result received from loopcmp.c
        printf("Received result from loopcmp.c: %d\n", result);

        // Close pipe ends
        close(pipe_to_loop[1]);
        close(pipe_from_loop[0]);
    }

    return 0;
}

loopcmp.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int main() {
    // Data buffers for receiving strings and integer
    char str1[100], str2[100];
    int number;

    // Read data from nicecmp.c through the pipe
    read(0, str1, sizeof(str1));
    read(0, str2, sizeof(str2));
    read(0, &number, sizeof(int));

    // Print the received data
    printf("Received strings from nicecmp.c: %s, %s\n", str1, str2);
    printf("Received integer from nicecmp.c: %d\n", number);

    // Send the number 20 back to nicecmp.c through the pipe
    int result = 20;
    write(1, &result, sizeof(int));

    return 0;
}

when Im trying to run ./nicecmp that's the result i get: enter image description here it's just going blank and doesn't show that the program is running.

What can I Do in order to solve the problem?

Thanks in advance :)

I Tried to do it with multiple pipes, 2 pipes for the strings and 1 pipe to the integer but couldn't solve it either.