C_MISTAKE, C programs which illustrate some simple but devious programming mistakes in C.
Note that because of the miserable random number interface in C, it's possible to not compute the sum of 100 random numbers in many interesting ways!
The computer code and data files made available on this web page are distributed under the GNU LGPL license.
C_MISTAKE is available in a C version and a FORTRAN77 version and a FORTRAN90 version and an HTML version and a MATLAB version.
You can go up one level to the C source codes.