How to add a char/int to an char array in C?

Question

How can I add \'.\' to the char Array := \"Hello World\" in C, so I get a char Array: \"Hello World.\" The Question seems simple but I\'m struggling.

Tried the follo

Answer 1

The error is due the fact that you are passing a wrong to strcat(). Look at strcat()'s prototype:

   char *strcat(char *dest, const char *src);

But you pass char as the second argument, which is obviously wrong.

Use snprintf() instead.

char str[1024] = "Hello World";
char tmp = '.';
size_t len = strlen(str);

snprintf(str + len, sizeof str - len, "%c", tmp);

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As commented by OP:

That was just a example with Hello World to describe the Problem. It must be empty as first in my real program. Program will fill it later. The problem just contains to add a char/int to an char Array

In that case, snprintf() can handle it easily to "append" integer types to a char buffer too. The advantage of snprintf() is that it's more flexible to concatenate various types of data into a char buffer.

For example to concatenate a string, char and an int:

char str[1024];
ch tmp = '.';
int i = 5;

// Fill str here

snprintf(str + len, sizeof str - len, "%c%d", str, tmp, i);