Rising posture series: fancy debugging information

#include <stdio.h>

#define logD(fmt, ...) \ fprintf(stdout, "[\e[34m debug \e[0m] %s:%02d --> ", __FILE__, __LINE__); fprintf(stdout, fmt, ##__VA_ARGS__);

#define logE(fmt, ...) \ fprintf(stderr, "[\e[31m error \e[0m] %s:%02d --> ", __FILE__, __LINE__); fprintf(stderr, fmt, ##__VA_ARGS__);

int main(){
    
    logD("%s\n", "here is debugging information");

    logE("%s %d %s\n", "error info", 123, "args");

    logD(" If not ##, This line compiles but ～\n");

    return 0;
}

effect ：

explain ：

Reference resources ： Erode yesterday

• #, Convert parameters to strings

#define P(x) printf("%s:%d\n",#x,x);

int a = 1, b = 2;
p(a + b);	//  Output ：a + b:3

• ##, Used to connect symbols

#define XNAME(n) x##n

int x3 = 3;
cout << XNAME(3);	//  Output ：3
P(XNAME(3));		//  Output ：XNAME(3):3

• __VA_ARGS__, yes C99 Macros with standard variable parameters , Equivalent to ellipsis in variable parameter function .
• ##__VA_ARGS__ , If not add ##, When the variable parameter is 0 when , A comma is added to the Hongzhan meeting , Causes compilation errors ,## To solve this problem .
• __FILE__, When the macro is expanded, it will be replaced with the current file name .
• __LINE__, When the macro is expanded, it will be replaced with the current line number .
• Terminal color code ,\e[30m Content \e[0m,\e[xm Pairs appear , The first number indicates the color , The ending number indicates the display effect .
  Color ：
  
  
  According to the effect ：
  0 No effect 1 bold 4 Underline 5 flashing 7 reverse 8 hide
• stdout, stderr, During terminal redirection ,stderr Still output to the screen .