It might be either static or dynamic analysis, preferably free.
cppcheck checks both C and C++ code and finds many errors.
Valgrind is a tool for runtime analysis, but I mention it anyway. It is extremely useful for tracking memory errors like uninitialized usage or leaks.
Also, activate ALL warnings your compiler has (GCC and clang: -Wall -Wpedantic -Wextra), which often reveals useful info.
Note: clang sometimes generates much better warnings/errors than GCC
To find logic errors, however, testing is required. Testing is required anyway, something that is not tested is per definition broken, as you cannot assume it works.
Wikipedia has a list of C unit testing software.