Difference between printf("%d") and printf("%d",x)

1. When we write printf("%d",x); the compiler will print the
value of x. But where there is nothing after %d so compiler will show  garbage value.

2. When we use %d the compiler internally uses it to access the
argument in the stack called argument stack. Compiler determines
the offset of the variable depending on the format specification
string. Now when we write printf("%d",x) then compiler first accesses the top most element in the argument stack of the printf which is %d and depending on the format string it calculated to offset to the actual data variable in the memory which is to be printed. Now when only %d will be present in the printf then compiler will calculate the correct offset (which will be the offset to access the integer variable) but as the actual data object is to be printed is not present at that memory location so it will print what ever will be the contents of that memory location.

3. Some compilers check the format string and will generate an error.