What is Wrong With My Code and What Does This Error Mean?

[Mr. Lemic]

 #include<stdio.h>
 int main(void)
 {
 char a; 
 a="?";
 }

Error i'm recieving:
warning: assignment makes integer from pointer without a cast
a="?";

[JamesCherrill]

A char is a one-byte integer value, used ti hold the ASCII value of a single character.
A string literal (enclosed in double quotes) is equivalent to an array of chars.
So on line 5 you are trying to assign an array (more precisely a pointer to an array) to an integer data type.
If you just want a single char then the correct syntax for the literal is to use single quotes, ie '?'

TLDR: a char and a one-character-long string are completely different animals.

[SwamiPete]

While the correct form of the assignment would, as JamesCherill says, certainly be:

a = '?';

a more illustrative correction might be:

a = "?"[0];