[SOLVED] Unexpected return from cin.getline() in C++

Question

I have this problem that when I use getline() function to input a char array it also inserts other characters, that are not constant and change every time I run the program.
I do realize it is most likely because of some kind of overflow happening, and it just takes numbers from the RAM.
But is there a possibility to fix that?
(Program is supposed to reverse a string and remove any non-letters, excluding spaces)

Here is my program:

#include <iostream>
#include <ctype.h>
#include <string>
using namespace std;

int main() {
string decoded = "";
char text[100];
cin.getline(text,sizeof(text));
for(int i = sizeof(text)-1; i >= 0; i--){
if (isalpha(text[i]) || text[i] == ' ' )
decoded.push_back(text[i]);
}
cout << decoded;
return 0;
}

Answer 1

The stray characters you are getting were not inserted by the getline call, but rather what is original stored within the memory locations now allocated to and held by your character array. Notice that the garbage values no longer appear if you initialize the array and overwrite all values held by those slots.

char text[100]{};

Answer 2

You're welcome! Extra references:

https://en.cppreference.com/w/c/language/array_initialization

"In C, the braced list of an initializer cannot be empty. C++ allows empty list:

int a[3] = {0}; // valid C and C++ way to zero-out a block-scope array
int a[3] = {}; // invalid C but valid C++ way to zero-out a block-scope array"

Answer 3

Thanks a tone bro!

Answer 4

I think it's good practice to use the function (
cin.ignor(); )
this well make the programm work well