C - Concatenate char (Not STRCAT)

Question

I have 2 variables: char x[100] and char c;

At first, I had to store c inside x. I did it this way:

x[0] = c;

Inside my program, after the previous run, the variable c value changes. Then I need to concatenate the value of c next to the x that has already been filled. I tried to do so:

x[strlen(x +1)] = c;

but did not resolve.

Using Strcat does not resolve.

Answer 1

Your problem is here strlen(x +1), the correct would be strlen(x) + 1.

Staying

x[strlen(x)+1] = c; 

Depending on your code you don’t even need add up 1, example:

#include <stdio.h>
#include <string.h>
#define TAMANHO 100

int main()
{
    char x[TAMANHO];
    memset(&x, '\0', sizeof(char)*TAMANHO);
    char c = 'a';
    x[strlen(x)] = c; // strlen(x) retorna 0 porque está vazio
    c = 'b';
    x[strlen(x)] = c; // strlen(x) retorna 1 porque já possui 1 elemento

    printf("%s", x);
    return 0;
}

Exit

ab

Ideone Exemplo

Changes suggested by ctgPi and jsbueno.