Output of C programs | Set 8

Predict the output of below C programs. 
Question 1:

Output: 

 10

Explanation: 
Please see standard printf function definition  

 int printf ( const char * format, ... );

format: String that contains the text to be written to stdout. It can optionally contain embedded format tags that are substituted by the values specified in subsequent argument(s) and formatted as requested. The number of arguments following the format parameters should at least be as much as the number of format tags. The format tags follow this prototype:  

 %[flags][width][.precision][length]specifier

You can see details of all above parts here https://cplusplus.com/reference/clibrary/cstdio/printf/.
The main thing to note is below the line about precision 
* (star): The width is not specified in the format string, but as an additional integer value argument preceding the argument that has to be formatted.

In simple words, the value to be printed must have atleast the number of characters corresponding to the width. Here the width is 5, the value to printed is 10. Since it just has two characters, in order to make it 5, three blank spaces will be printed preceding 10.

So 10 gets printed after 3 spaces!!
Question 2 

Output:  hffltgpshfflt
Explanation: 
The crust of this question lies in expression ++*ptr++.
If one knows the precedence and associativity of the operators then there is nothing much left. Below is the precedence of operators. 

 Postfix ++ left-to-right
 Prefix ++ right-to-left
 Dereference * right-to-left

Therefore the expression ++*ptr++ has following effect 
Value of *ptr is incremented 
Value of ptr is incremented
Question 3 

Output: -128
Explanation: 
Here, the first thing to be noticed is the semi-colon in the end of for loop. So basically, there's no body for the for loop. And printf will print the value of i when control comes out of the for loop. Also, notice that the first statement i.e. initializer in the for loop is not present. But i has been initialized at the declaration time. Since i is a signed character, it can take value from -128 to 127. So in the for loop, i will keep incrementing and the condition is met till roll over happens. At the roll over, i will become -128 after 127, in that case condition is not met and control comes out of the for loop.
Question 4 

Output: Compiler error.
Explanation: 
Parameter passed to fun() and parameter expected in definition are of incompatible types. fun() expects const char** while passed parameter is of type char **.
Now try following program, it will work. 

void fun(const char **p) { }
int main(int argc, char **argv)
{
 const char **temp;
 fun(temp);
 getchar();
 return 0;
}