Function not declared in this scope

Question

I dont know how to declare this function.

Error: In function \'int main(int, char**).
line 25 colume 16 [Error] \'histo

Answer 1

Functions need to be declared before they're used in C. Either move the definition of histogram up above main, or add

void histogram(char[N][M]);

to the top of the file.

Answer 2

You will need to define that function before it is used. For larger programs it is usually helpful to have a header file, though not needed for a single function. Just place a

void histogram(char[N][M]);

at the top of your file before MAIN. If you continue to add things, I suggest using a header file though.