How to assign a value to a char* using hex notation?

Question

I usually use pointers in the following manner

    char *ptr = malloc( sizeof(char) * 100 );
    memset( ptr, 0, 100 ) ;
    strncpy( ptr, \"cat\" , 100 - 1 );

Answer 1

\xXX is the syntax for inserting characters in hex format. so yours would be:

strncpy( ptr, "\x63\x61\x74", 100 - 1);

You don't need to put in a \x00 since having quotes automatically null-delimits the string.