Why strcat(string'!') not work in C program?

Answer 1

The strcat() function has the following protocol:

char* strcat (char* destination, char* source);

The function appends the source string to the destination string and returns the destination string.

The destination string must be a null-terminated character array of sufficient length to accommodate strlen (source) plus strlen (destination) characters, plus a null-terminator. The existing null-terminator and subsequent characters of destination are overwritten by characters from the source string, up to and including the source string's null-terminator.

strcat (string, '!') will not work because '!' is a character literal (ASCII code 33 decimal), not a null-terminated character array. Use "!" instead of '!'.

Example:

char string[80]; // character array

strcpy (string, "Hello world");

strcat (string, "!");

puts (string);