Logging

A macro that allows logging using the insertion (<<) operator for C++.

Usage

LOG(level) << expr1 << expr2 << ...;

level is the log level. expr can be any expression.

Only log messages with a level greater than or equal to the LOGLEVEL macro are output. Compile your program with -DLOGLEVEL=level to specify the minimum log level. All log messages are output to stderr.

Available log levels:

DEBUG       0
INFO        1
WARNING     2
ERROR       3
CRITICAL    4

Example

#include <exception>

#include "logging.h"

int main(int argc, char** argv) {
    int x = 5, y = 10, z;

    // LOGLEVEL=1
    LOG(INFO) << "Running program...";

    // LOGLEVEL=0
    z = x + y;
    LOG(DEBUG) << "x+y = " << z;

    // LOGLEVEL=2
    z = x;
    if (z < y) {
        LOG(WARNING) << "z=" << z << " is less than y=" << y;
    }

    // LOGLEVEL=3
    z = x + y + 1;
    if (z != x + y) {
        LOG(ERROR) << "z=" << z << " is not equal to x+y=" << x + y;
    }

    // LOGLEVEL=4
    try {
        int* large_array = new int[1000000000000];
    } catch (std::exception& e) {
        LOG(CRITICAL) << e.what();
    }

    return 0;
}

Output:

[INFO]      logging.cpp:9: Running program...
[DEBUG]     logging.cpp:13: x+y = 15
[WARNING]   logging.cpp:18: z=5 is less than y=10
[ERROR]     logging.cpp:24: z=16 is not equal to x+y=15
[CRITICAL]  logging.cpp:31: std::bad_alloc

Distribution

Refer to the logging.h file for licensing information.