generic way to print out variable name in c++

user_448839 0
Viewed 24930

given a class 

struct {
  int a1;
  bool a2;
  ...
  char* a500;
  ...
  char a10000;      
}

I want to print or stream out 

"a1 value is SOME_VALUE"  
"a2 value is SOME_VALUE"
"a500 value is SOME_VALUE"
...
"a10000 value is SOME_VALUE"

the type of the member variables are not the same (mainly, int, bool, char*, etc, i.e., no need to overload << operator), and the member variable name could be named with anything, i.e., no rule to follow. Instead of typing explicitely one by one (very big tedious, and error-prone work), is there any generic way?

Thanks for any comments!

iostream printf variables c++
6 Answers

The watch macro is one of the most useful tricks ever.

#define watch(x) cout << (#x) << " is " << (x) << endl

If you’re debugging your code, watch(variable); will print the name of the variable and its value. (It’s possible because it's built during preprocessing time.)

user_98710940

GDB can print structs. This script generates gdb script to set breakpoints and print values at specified by gdb_print locations:

gdb-print-prepare()
{

    # usage:
    # mark print points with empty standalone defines:
    # gdb_print(huge_struct);
    # gdb-print-prepare $src > app.gdb
    # gdb --batch --quiet --command=app.gdb $app
    cat  <<-EOF
    set auto-load safe-path /
    EOF
    grep --with-filename --line-number --recursive '^\s\+gdb_print(.*);' $1 | \
    while IFS=$'\t ;()' read line func var rest; do
        cat  <<-EOF
        break ${line%:}
        commands
        silent
        where 1
        echo \\n$var\\n
        print $var
        cont
        end
        EOF
    done
    cat  <<-EOF
    run
    bt
    echo ---\\n
    EOF
}

From https://gitlab.com/makelinux/lib/blob/master/snippets/gdb-print-prepare.md

user_7942140
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