readInput Module

A simple C module for reading and parsing user input into different types using a union structure.

Description

This module provides a function readInput() to handle typed user input (string, integer, or double) and store it efficiently in a union structure (type_3). It helps avoid repetitive boilerplate code when reading different types of input from the user and provides memory safety by allowing dynamic allocation.

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Files

• readInput.c: Implements the input parsing logic and buffer flushing.
• readInput.h: Declares the readInput interface and the type_3 union structure.

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Function Usage

type_3 *readInput(char *Chaine, int taille, char mode, type_3 *Variable);

Parameters:

1. Chaine: Buffer to read the input string into.
2. taille: Size of the buffer.
3. mode: Character flag to indicate the data type:
   • 's' → string
   • 'l' → long (integer)
   • 'd' → double (floating-point)
4. Variable: A pointer to a type_3 variable. On first use, pass NULL; reuse the returned pointer for subsequent calls to avoid memory leaks.

Returns:
A pointer to a type_3 union that contains the parsed value (string, long, or double).

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Example Usage

Uncomment the example in readInput.c to test the function:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "readInput.h"

int main(int argc, char *argv[]) {
    char Chaine[PC_TAILLE] = "";
    type_3 *Var = NULL;

    printf("Entrez votre nom:\n");
    Var = readInput(Chaine, PC_TAILLE, 's', NULL);
    printf("Ah! Vous vous appelez donc %s\n", Var->Chaine);

    printf("Quel est votre age:\n");
    readInput(Chaine, PC_TAILLE, 'l', Var);
    printf("Ah! Vous êtes âgé de %ld ans\n", Var->entier);

    printf("Quel est votre moyenne du premier semestre:\n");
    readInput(Chaine, PC_TAILLE, 'd', Var);
    printf("Ah! Vous avez eu %lf de moyenne\n", Var->reel);

    free(Var); // Always free allocated memory
    return 0;
}

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Structure Definition

#define PC_TAILLE 100

union type_3 {
    char Chaine[PC_TAILLE];
    long entier;
    double reel;
};
typedef union type_3 type_3;

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⚠️ Notes

• Always pass NULL for the first use of readInput(), and reuse the returned pointer for later calls.
• Don’t forget to call free() on the returned pointer when you're done using it.
• The internal buffer cleaning is handled to avoid unwanted input effects.

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