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<!DOCTYPE html>
<html dir="ltr" lang="en">
<head>
<meta charset='utf-8'>
<title>C & GDB</title>
</head>
<body>
<a href="index.html">C Index</a>
<h1>Hello World</h1>
<p>C "allows to implement" or approach to various
programming paradigms but due to it's characteristics
it's more a procedural language. C procedural programs
are divided in smaller procedures, or functions, and
data or pointers to data are passed into them or is
shared between them. To get started create file
hello.c with;</p>
<pre>
#include <stdio.h>
int main() {
printf("Hello World!");
return 0;
}
</pre>
<p>Compile;</p>
<pre>
$ gcc -Wall hello.c -o hello
</pre>
<p>Run;</p>
<pre>
$./hello
Hello World!
</pre>
<h2 id="makefile">Makefile</h2>
<p>Make reads a Makefile by default on current directory,
Makefile defines targets, for example executables and their
dependencies, for example object files and source files.<p>
<p>Create Makefile;</p>
<pre>
CC=gcc
CFLAGS=-Wall
hello: main.o hello.o
clean:
rm -f hello main.o hello.o
</pre>
<pre>
$ touch NEWS README AUTHORS ChangeLog
</pre>
<h2 id="debug">Debug</h2>
<p>To use gdb you need to compile program with -g flag. Change
Makefile</p>
<pre>
CC=gcc
CFLAGS=-Wall -g
hello: main.o hello.o
clean:
rm -f hello main.o hello.o
</pre>
<pre>
$ gdb hello
</pre>
<p>Set break point;</p>
<pre>
(gdb) break main
</pre>
<p>To start the program you can type run, this way gdb
will try to run the program until the end. If program
crash, gdb will stop it for debuging. Start program;</p>
<pre>
(gdb) run
</pre>
<p>Step in next line;</p>
<pre>
(gdb) s
</pre>
<p>Print variable "name" value;</p>
<pre>
(gdb) print name
$1 = 0x4005b0 "world"
(gdb)
</pre>
<p>Print variable "name" type;</p>
<pre>
(gdb) ptype name
type = const char *
(gdb)
</pre>
<p>Variable is a <a href="elements.html#const">string constant</a>.
Execute next line to end;</p>
<pre>
(gdb) n
</pre>
<a href="index.html">C Index</a>
<p>
This is part of the LeetIO System Documentation.
Copyright (C) 2021
LeetIO Team.
See the file <a href="../../fdl-1.3-standalone.html">Gnu Free Documentation License</a>
for copying conditions.</p>
</body>
</html>
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