How to use scanf in C.

A lot of new C programmers have trouble with scanf(). 

The main reason beginners have trouble is scanf works like a pointer so you have to point to what you are getting input for
 

<pre class="prettyprint lang-auto linenums:0">

#include<stdio.h>

int main()
{
int myvariable;

printf("Enter a number:");
scanf("%d",&myvariable);
printf("%d",myvariable);

return 0;
}</pre>

 
See, when we used scanf we first declared what the variables type was
"%d" for int ,"%f" for float ,"%e" for a scientific notation (1e10) ,"%c" for char , "%s" for strings.

Then in the second part we have to use & just like in a pointer to point to the variable instead of just getting its value.
Remember without & your program will likely crash.

For handling strings with whitespace (sentences) and in files use fgets.