为什么我会出现堆栈溢出？ 建议将不胜感激

Question

So, I'm very new to coding and i do apologize beforehand if my code makes you cringe. I have a coding homework to write a program that displays the c_string in all uppercase characters using a recursive function. When running my code, i get an out put of "A" then i get a stack overflow and i don't know why. Please assist me to help me understand where i went wrong with my code. Also, if you have any advice on how i should have coded differently for this problem, please let me know!

I tried changing using a for loop but I'm reading online that its an iteration function and doesn't work with recursive.

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

void showInUpper(char alphabet[], int i);


int main()
{

char alphabet[27]{ "abcdefghijklmnopqrstuvwxyz" };
int i = 0;

showInUpper(alphabet, i);

cout << endl << endl;
}

void showInUpper(char alphabet[], int i)
{

if (alphabet[i] == '\0')
{
    return;

}

else if (alphabet[i] != toupper(alphabet[i]))
{
    alphabet[i] = toupper(alphabet[i]);
    cout << alphabet[i] << '\t';
}

showInUpper(alphabet, i++);
}

So, the expected results should look like this.

ABCDEFGHIJKLMNOPQRSTUVWZXYZ

Answer 1

You're passing the same value of i to each invocation of showInUpper because i doesn't get incremented until after it is passed to the function. As a result you have endless recursion.

Use the pre-increment operator instead:

showInUpper(alphabet, ++i);

so that i is incremented before it is passed.