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# 2. Create and build a "Hello world" application

Follow these steps to create and build a "Hello world" application:

1. Create a directory called hello_world:

    ~> mkdir hello_world

2. Inside the hello_world directory, create a file named hello-world.c:

    ~> cd hello_world
    ~> touch hello-world.c

3. Edit the hello-world.c file with the following contents:

    hello-world.c

    #include <stdio.h>
    #include <unistd.h>

    int main(int argc, char *argv[]){
        int i;

        for (i = 1; i <= 10; i++) {
        printf("%d - Hello world!\n", i);
            sleep(1);
        }

        return 0;
    }

4. Create a makefile file inside the hello_world directory:

    ~> touch Makefile

5. Edit the file Makefile with the following contents:

    Makefile

    BINARY := hello-world
    CFLAGS += -Wall -O0

    .PHONY: all
    all: $(BINARY)

    $(BINARY): hello-world.o

    .PHONY: clean
    clean:
    -rm -f *.o $(BINARY)

6. Before building the code, export the toolchain environment:

    ~> . /opt/dey/2.2-r3/environment-setup-cortexa7hf-neon-dey-linux-gnueabi

7. Cross-compile the code using make.

    ~> make

Note If you are building a Qt application, run qmake before cross-compiling:

    ~> qmake

The binary file, hello-world, is generated inside the directory hello_world.

    ~> ls -l
    total 28
    -rwxrwxr-x 1 user user 12084 dic 18 12:39  hello-world
    -rw-rw-r-- 1 user user   199 dic 18 12:39 hello-world.c
    -rw-rw-r-- 1 user user  4968 dic 18 12:39 hello-world.o
    -rw-rw-r-- 1 user user   189 dic 18 12:39 Makefile

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2. Create and build a "Hello world" application updated on 22 January 2018 02:43:38 PM