Why use symbol & when using scanf in C?

[jd12345]

Why use symbol "&" when using scanf in C?

When using scanf like in scanf("%d",&x); why do we use '&' before x? can't we write directly ,x as in printf command? Is it just a convention? I think it should have a reason.. they won't just put an "&" just like that

 

[rcgldr]

"&x" means to generate a pointer to "x". Scanf needs a pointer to x in order to store the value and change "x". Printf uses a copy of the value of "x" passed as a parameter (usually on the stack), since it isn't changing the value of "x".