check-input-int-float_phuong

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

/* Check input int number [min, max] with maximum range-digit */
int intcheck(int min, int max, int range, char msg[], char err[]) {
    int num, i, check, len;
    char *x;

    x = (char *) malloc(range * sizeof(char));
    while (1) {
        printf("%s", msg);
        fflush(stdin);
        scanf("%[^\n]", x);
        check = 1; len = strlen(x);
        if (len > 0 && len <= range) {  // check validation string
            for (i = 0; i < len; i++) {  // check validation int number
                if (x[i] < '0' || x[i] > '9') {
                    check = 0;
                    break;
                }
            }
            if (check == 1) {  // if it is a int number, convert string ~> int
            num = atoi(x);
            if (num >= min && num <= max)
                return(num);
            }
        }
        printf("%s", err);
    }
    free(x);
}

/* Check input float number in range (min, max] */
double floatcheck(double min, double max, char msg[], char err[]) {
    double num;
    char *x;
    int i, check;

    x = (char *) malloc(20 * sizeof(char));
    while (1) {
        printf("%s", msg);
        fflush(stdin);
        scanf("%[^\n]", x);
        check = 1;
        if (strlen(x) > 0 && strlen(x) < 20) {  // check validation string
            for (i = 0; i < strlen(x); i++) {  // check validation double number
                if (x[i] < '0' || x[i] > '9') {
                    if (x[i] != '.') {
                        check = 0;
                        break;
                    }
                }
            }
            if (check == 1) {  // if it is a float number, convert string ~> double
                num = atof(x);
                if (num > min && num <= max)
                    return(num);
            }
        }
        printf("%s", err);
    }
    free(x);
}

int main(){
    char msg[] = "Enter a int number in range [1,255]: ";
    char err[] = "Invalid input, please re-enter.\n";
    int n = intcheck(1, 255, 3, msg, err);
    //int n = inputcheck(1, 255, 3, "Enter a number in range [1,255]: ", "Invalid input, please re-enter.\n");
    printf("%d\n", n);

    strcpy (msg, "Enter a float number in range (0, ..] ");
    double x = floatcheck(0, DBL_MAX, msg, err);
    printf("%lf\n", x);
    return 0;
}