A simple C WinAPI program for terminating processes via process image names - follow-up
Regarding:
size_t totalProcessesMatched = 0;
size_t totalProcessesTerminated = 0;
...
printf(&quot;Info: total matching processes: %d, total terminated: %d.\n&quot;, 
       totalProcessesMatched, 
       totalProcessesTerminated);

the printf() is trying to output a int, but the variables to output are size_t which should be output using a %zu format specifier.
If you compiler is not telling you about these kinds of problems, then enable the warnings until it does.
regarding;
fprintf(stderr, &quot;processkiller.exe PROCESS_NAME&quot;);  

This would be 1) left in the stderr output stream because the format string does not have a \n on the end of it.  2) any program can be executed via any name so hard coding the name is a bad idea.  Suggest:
fprintf(stderr, &quot;%s PROCESS_NAME\n&quot;, argv[0] );

regarding:
fputs(&quot;Error: could not get the process snapshot.&quot;, stderr);

strongly suggest making use of the get_last_error() facility and printing the actual error text to stderr rather than some 'random' error message
regarding;
if (strcmp(entry.szExeFile, argv[1]) == 0) {

this does not compile because the statement:
#include &lt;string.h&gt;

is missing.