Note: C++ uses the extension .CPP. You can write and compile your C programs
with a .CPP extension, but it’s more appropriate to use a .C extension.- FILENAME.TXT would compile. However, it’s more appropriate to use a .C
extension rather than .TXT. - You should make changes to the source code to correct the problems. You should
then recompile and relink. After relinking, you should run the program again to see
whether your corrections fixed the program. - Machine language is made up of digital or binary instructions that the computer
can understand. Because the computer can’t understand C source code, a compiler
translates source code to machine code, also called object code. - The linker combines the object code from your program with the object code from
the function library and creates an executable file.
Exercises
- When you look at the object file, you see many unusual characters and other gib-
berish. Mixed in with the gibberish, you also see pieces of the source file. - This program calculates the area of a circle. It prompts the user for the radius and
then displays the area. - This program prints a 10×10 block made of the character X. A similar program is
covered on Day 6, “Basic Program Control.” - This program generates a compiler error. You should get a message similar to the
following:
Error: ch1ex4.c: Declaration terminated incorrectly
This error is caused by the semicolon at the end of line 3. If you remove the semi-
colon, this program should compile and link correctly. - This program compiles OK, but it generates a linker error. You should get a mes-
sage similar to the following:
Error: Undefined symbol _do_it in module...
This error occurs because the linker can’t find a function called do_it. To fix this
program, change do_ittoprintf. - Rather than printing a 10×10 block filled with the character X, the program now
prints a 10×10 block of smiley faces.
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