Compiler warning – suggest parentheses around assignment used as truth value
Be explicit – then the compiler won’t warn that you perhaps made a mistake. or Some day you’ll be glad the compiler told you, people do make that mistake 😉
compiler-warnings
Multi-character constant warnings
According to the standard (§6.4.4.4/10) The value of an integer character constant containing more than one character (e.g., ‘ab’), […] is implementation-defined. This is valid ISO 9899:2011 C. It compiles without warning under gcc with -Wall, and a “multi-character character constant” warning with -pedantic. From Wikipedia: Multi-character constants (e.g. ‘xy’) are valid, although rarely useful …
c array – warning: format not a string literal
When using printf, the format string is better be a string literal and not a variable:
warning: implicit declaration of function
You are using a function for which the compiler has not seen a declaration (“prototype“) yet. For example: You need to declare your function before main, like this, either directly or in a header:
What does “control reaches end of non-void function” mean?
The compiler cannot tell from that code if the function will ever reach the end and still return something. To make that clear, replace the last else if(…) with just else.
warning: implicit declaration of function
You are using a function for which the compiler has not seen a declaration (“prototype“) yet. For example: You need to declare your function before main, like this, either directly or in a header:
warning: implicit declaration of function
You are using a function for which the compiler has not seen a declaration (“prototype“) yet. For example: You need to declare your function before main, like this, either directly or in a header: