Append Char To String in C?

Question

How do I append a single char to a string in C?

i.e

char* str = \"blablabla\";
char c = \'H\';
str_append(str,c); /* blablablaH */

Answer 1

The Original poster didn't mean to write:

  char* str = "blablabla";

but

  char str[128] = "blablabla";

Now, adding a single character would seem more efficient than adding a whole string with strcat. Going the strcat way, you could:

  char tmpstr[2];
  tmpstr[0] = c;
  tmpstr[1] = 0;
  strcat (str, tmpstr);

but you can also easily write your own function (as several have done before me):

  void strcat_c (char *str, char c)
  {
    for (;*str;str++); // note the terminating semicolon here. 
    *str++ = c; 
    *str++ = 0;
  }

Answer 2

Easiest way to append two strings:

char * append(char * string1, char * string2)
{
    char * result = NULL;
    asprintf(&result, "%s%s", string1, string2);
    return result;
}

Answer 3

char* str = "blablabla";     

You should not modify this string at all. It resides in implementation defined read only region. Modifying it causes Undefined Behavior.

You need a char array not a string literal.

Good Read:
What is the difference between char a[] = "string"; and char *p = "string";