Graphics Programs Reference
In-Depth Information
7 - Hello, world!
8 - Hello, world!
9 - Hello, world!
10 - Hello, world!
11 - Hello, world!
reader@hacking:~/booksrc $
Format strings are used quite often, so familiarity with them is valuable.
In addition, the ability to output the values of variables allows for debugging in
the program, without the use of a debugger. Having some form of immediate
feedback is fairly vital to the hacker's learning process, and something as
simple as printing the value of a variable can allow for lots of exploitation.
0x265
Typecasting
Typecasting
is simply a way to temporarily change a variable's data type, despite
how it was originally defined. When a variable is typecast into a different
type, the compiler is basically told to treat that variable as if it were the
new data type, but only for that operation. The syntax for typecasting is
as follows:
(
typecast_data_type) variable
This can be used when dealing with integers and floating-point variables,
as typecasting.c demonstrates.
typecasting.c
#include <stdio.h>
int main() {
int a, b;
float c, d;
a = 13;
b = 5;
c = a / b; // Divide using integers.
d = (float) a / (float) b; // Divide integers typecast as floats.
printf("[integers]\t a = %d\t b = %d\n", a, b);
printf("[floats]\t c = %f\t d = %f\n", c, d);
}
The results of compiling and executing typecasting.c are as follows.
reader@hacking:~/booksrc $ gcc typecasting.c
reader@hacking:~/booksrc $ ./a.out
[integers] a = 13 b = 5
[floats] c = 2.000000 d = 2.600000
r
eader@hacking:~/booksrc $
