double output from tolower() c

Question

the while works however in the end the "selezione" variable becomes double for example by inserting FA the variable will become faFA and this does not allow the if to work. i know that there is an error but i cant find it, i am not that good so as u can see in my name dont insult me :)

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <ctype.h>

int main(){
    int i=0;
    double fa,ce,ke;
    char selezione[2];

    printf("Scegli l'unita di misura da convertire:\n\n digita fa per fahrenheit\n digita ce per celsius \n digita ke per kelvin \n");      //selezione unità di misura
    gets(selezione);

    while (selezione[i]){
        putchar(tolower(selezione[i]));
        i++;
    }
    puts(selezione);

    if (strcmp(selezione,"fa")==0) {
        printf("Inserisci il valore fahrenheit da convertire: ");
        scanf("%lf",&fa);
        ce=(fa-32)/1.8;                                                                                 //conversione da fahrenheit
        ke=((5/9.0)*(fa-32))+273.15;
        printf("%f fahrenheit sono:\n%f gradi celsius\n%f kelvin",fa,ce,ke);

    }

    else if (strcmp(selezione,"ce")==0){
        printf("Inserisci il valore celsius da convertire: ");
        scanf("%lf",&ce);
        fa=(ce*(9/5.0))+32;                                                                             //conversione da celsius
        ke=ce+273.15;
        printf("%f gradi celsius sono:\n%f fahrenheit\n%f kelvin",ce,fa,ke);
    }

    else if (strcmp(selezione,"ke")==0){
        printf("Inserisci il valore kelvin da convertire: ");
        scanf("%lf",&ke);
        fa=((ke-273.15)*(9/5))+32;                                                                      //conversione da kelvin
        ce=(ke-273.15);
        printf("%f kelvin sono:\n%f fahrenheit\n%f fradi celsius",ke,fa,ce);
    }

    else {
        printf("Carattere non riconosciuto, riprova");
    }
}

`gets(selezione);` This will overrun the 2-char buffer. `puts(selezione);` Why? — dxiv, Oct 25 '20 at 18:04
`char selezione[2];` does not provide enough room for a null terminator after two characters. Make the array larger. — Eric Postpischil, Oct 25 '20 at 18:05
The `char selezione[2]; gets(selezione);` will break something because the array is too small. Never use `gets`, it is no longer part of the standard C library. Please read [Why is the gets function so dangerous that it should not be used?](https://stackoverflow.com/questions/1694036/why-is-the-gets-function-so-dangerous-that-it-should-not-be-used) — Weather Vane, Oct 25 '20 at 18:06
@imnewplsdontinsultme `just for verify the variable` That's the "*double output*". — dxiv, Oct 25 '20 at 18:07
The translation into lower cases is failing. Why do you call putchar(tolower(...)) ? Just do : selezione[i] = tolower(selezione[i]) in the loop. — Rachid K., Oct 25 '20 at 18:07
@RachidK. thank you thank you and thank you again now it works now I understand why I found the double variable — imnewplsdontinsultme, Oct 25 '20 at 18:13

double output from tolower() c

0 Answers0