Linux下的GCC实用粗谈

男娘i 2022-06-01 05:07 119阅读 0赞

# GCC编译 #

GCC（GNU C Compiler）是GNU推出的功能强大、性能优越的多平台编译器，是GNU的代表作之一。

##### 1.一般用法 #####

[klaus@localhost my_usual]$ clear
    [klaus@localhost my_usual]$ ll
    total 4
    -rw-rw-r--. 1 klaus klaus 99 Jan 20 19:33 hello.c
    [klaus@localhost my_usual]$ cat hello.c 
    #include<stdio.h>
    
    int main(int argc ,char **argv)
    {
        printf("hello world!\n");
        return 0;
    }
    [klaus@localhost my_usual]$ gcc hello.c -o hello
    [klaus@localhost my_usual]$ ll
    total 12
    -rwxrwxr-x. 1 klaus klaus 4647 Jan 20 20:04 hello
    -rw-rw-r--. 1 klaus klaus   99 Jan 20 19:33 hello.c
    [klaus@localhost my_usual]$ ./hello 
    hello world!
    [klaus@localhost my_usual]$

##### 2.优化编译，提高性能 #####

[klaus@localhost my_usual]$ gcc -O hello.c -o hello

##### 3.添加文件路径 #####

gcc在系统预设的头文件目录(如/usr/include)中搜寻相应的文件，如果要编译的头文件不在里面，可通过-I告诉编译在哪！

[klaus@localhost my_usual]$ ll
    total 8
    -rw-rw-r--. 1 klaus klaus   97 Jan 20 20:20 hello.c
    drwxrwxr-x. 2 klaus klaus 4096 Jan 20 20:21 include
    [klaus@localhost my_usual]$ cd include/
    [klaus@localhost include]$ ll
    total 4
    -rw-rw-r--. 1 klaus klaus 18 Jan 20 20:21 test.h
    [klaus@localhost include]$ cat test.h 
    #include"stdio.h"
    [klaus@localhost include]$ cd ..
    [klaus@localhost my_usual]$ cat hello.c 
    #include"test.h"
    int main(int argc ,char **argv)
    {
        printf("hello world!\n");
        return 0;
    }
    [klaus@localhost my_usual]$ gcc hello.c
    hello.c:1:17: error: test.h: No such file or directory
    hello.c: In function ‘main’:
    hello.c:4: warning: incompatible implicit declaration of built-in function ‘printf’
    [klaus@localhost my_usual]$ gcc hello.c -I ./include/ -o hello
    [klaus@localhost my_usual]$ ll
    total 16
    -rwxrwxr-x. 1 klaus klaus 4647 Jan 20 20:24 hello
    -rw-rw-r--. 1 klaus klaus   97 Jan 20 20:20 hello.c
    drwxrwxr-x. 2 klaus klaus 4096 Jan 20 20:21 include
    [klaus@localhost my_usual]$ ./hello 
    hello world!

##### 4.警告处理 #####

###### 1.不显示警告 ######

[klaus@localhost my_usual]$ cat hello.c
    #include "stdio.h"
    int main(int argc ,char **argv)
    {
        int i = "c";
        printf("hello world!\n");
        return 0;
    }
    [klaus@localhost my_usual]$ gcc hello.c -o hello
    hello.c: In function ‘main’:
    hello.c:4: warning: initialization makes integer from pointer without a cast
    [klaus@localhost my_usual]$ gcc -w hello.c -o hello
    [klaus@localhost my_usual]$ ./hello 
    hello world!
    [klaus@localhost my_usual]$ ll

###### 2.显示所有警告 ######

[klaus@localhost my_usual]$ gcc -Wall hello.c -o hello

##### 5.宏处理选项 #####

> \-D+宏名称

[klaus@localhost my_usual]$ cat hello.c 
    #include "stdio.h"
    
    int main(int argc ,char **argv)
    {
    #ifdef PRE_DEAL
        printf("hello world!\n");
    #endif
        return 0;
    }
    [klaus@localhost my_usual]$ gcc hello.c 
    [klaus@localhost my_usual]$ ./a.out 
    [klaus@localhost my_usual]$ gcc -DPRE_DEAL hello.c 
    [klaus@localhost my_usual]$ ./a.out 
    hello world!
    [klaus@localhost my_usual]$