Recursion in c to print characters

Question

I need to write a function that receive two arguments, n and 2 characters, from void main and then to print the first character n times and the second character n*2. I can only use recursion, not strings or anything more advanced. I tried different variations but after the recursion the prog isn't going down to the statement of printf to print ch2 twice. can someone help?

Thanks in advance.

#include<stdio.h>
void string_rec(int num, char ch1, char ch2)
{
    if (num == 0)
        return 0;
    else
    {
        printf("%c",ch1);
        return string_rec(num-1, ch1, ch2);
        printf("%c%c", ch2, ch2);
    }
}

Answer 1

它不会去那里，因为return停止了该功能。二printf是遥不可及。删除那个return。

void string_rec(int num, char ch1, char ch2)
{
    if (num == 0)
        return;
    else
    {
        printf("%c", ch1);
        string_rec(num - 1, ch1, ch2); // don't return here
        printf("%c%c", ch2, ch2);
    }
}
int main() {
    string_rec(5, 'a', 'b');
}

此外，由于该函数被定义为返回void，请将return 0;上述更改为return;。如果你愿意，你也可以像这样简化它：

void string_rec(int num, char ch1, char ch2)
{
    if (num != 0)
        return;
    printf("%c", ch1);
    string_rec(num - 1, ch1, ch2);
    printf("%c%c", ch2, ch2);

}