Ubuntu Unleashed 2019 Edition: Covering 18.04, 18.10, 19.04

matthew@seymour:~$  gcc -o  tux tux.c

matthew@seymour:~$  ./tux

But the splint command might point out some serious problems with the
source:

Click here to view code image
matthew@seymour:~$ splint tux.c
Splint 3.1.2 -- 29 Apr 2009

tux.c:  (in function    main)

tux.c:2:19: Return  value   (type   int)    ignored:    putchar(t[++j]  -...

        Result  returned    by  function    call    is  not used.   If  this    is  intended,

can cast

        result  to  (void)  to  eliminate   message.    (Use    -retvalint  to  inhibit

warning)

Finished    checking    --  1   code    warning

You can use the splint command’s -strict option, like this, to get a more
verbose report:

Click here to view code image
matthew@seymour:~$ splint -strict tux.c

gcc also supports diagnostics through the use of extensive warnings (through
the -Wall and -pedantic options):

Click here to view code image
matthew@seymour:~$ gcc -Wall tux.c
tux.c:1: warning: return type defaults to 'int'
tux.c: In function 'main':
tux.c:2: warning: implicit declaration of function 'putchar'

Using gprof to Track Function Time

You use the gprof (profile) command to study how a program is spending
its time. If a program is compiled and linked with -p as a flag, a mon.out
file is created when it executes, with data on how often each function is called
and how much time is spent in each function. gprof parses and displays this
data. An analysis of the output generated by gprof helps you determine
where performance bottlenecks occur. Using an optimizing compiler can
speed up a program, but taking the time to use gprof’s analysis and revising
bottleneck functions significantly improves program performance.

Doing Symbolic Debugging with gdb