C Programming Questions and Answers - Precedence and Order of Evaluation - 5

This set of C Multiple Choice Questions & Answers (MCQs) focuses on “Precedence and Order of Evaluation – 5”.

Pre-requisite for this C MCQ set: Advanced C Programming Video Tutorial.

1. What will be the output of the following C function?

```
    #include <stdio.h>
```
```
    void reverse(int i);
```
```
    int main()
```
```
    {
```
```
        reverse(1);
```
```
    }
```
```
    void reverse(int i)
```
```
    {
```
```
        if (i > 5)
```
```
            exit(0);
```
```
        printf("%d\n", i);
```
```
        return reverse(i++);
```
```
    }
```

a) 1 2 3 4 5
b) 1 2 3 4
c) Compile time error
d) Stack overflow
View Answer

Answer: d
Explanation: None.

2. What will be the output of the following C function?

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```
    #include <stdio.h>
```
```
    void reverse(int i);
```
```
    int main()
```
```
    {
```
```
        reverse(1);
```
```
    }
```
```
    void reverse(int i)
```
```
    {
```
```
        if (i > 5)
```
```
            return ;
```
```
        printf("%d ", i);
```
```
        return reverse((i++, i));
```
```
    }
```

a) 1 2 3 4 5
b) Segmentation fault
c) Compilation error
d) Undefined behaviour
View Answer

Answer: a
Explanation: None.

3. In expression i = g() + f(), first function called depends on __________
a) Compiler
b) Associativiy of () operator
c) Precedence of () and + operator
d) Left to write of the expression
View Answer

Answer: a
Explanation: None.

4. What will be the final values of i and j in the following C code?

```
    #include <stdio.h>
```
```
    int x = 0;
```
```
    int f()
```
```
    {
```
```
        if (x == 0)
```
```
            return ++x;
```
```
        else
```
```
            return --x;
```
```
    }
```
```
    int g()
```
```
    {
```
```
        return x++;
```
```
    }
```
```
    int main()
```
```
    {
```
```
        int i, j;
```
```
        i = (f() + g()) || g();
```
```
        x = 0;
```
```
        j = g() || (f() + g());
```
```
    }
```

a) i value is 1 and j value is 1
b) i value is 0 and j value is 0
c) i value is 1 and j value is undefined
d) i and j value are undefined
View Answer

Answer: d
Explanation: Logical OR are evaluated strictly from left-to-right. The ‘+’ operator has two operands f() & g() and these functions f() and g() can get evaluated in any order depending on the compiler. When x is 0, (f() + g()) can return values of either 0 or 2 depending on the order of evaluation of these functions by the compiler. Hence, we can’t have a fixed value for i and j.

5. What will be the final values of i and j in the following C code?

```
    #include <stdio.h>
```
```
    int x = 0;
```
```
    int f()
```
```
    {
```
```
        if (x == 0)
```
```
            return x + 1;
```
```
        else
```
```
            return x - 1;
```
```
    }
```
```
    int g()
```
```
    {
```
```
        return x++;
```
```
    }
```
```
    int main()
```
```
    {
```

        int i = (f() + g()) | g(); //bitwise or

        int j = g() | (f() + g()); //bitwise or

```
    }
```

a) i value is 1 and j value is 1
b) i value is 0 and j value is 0
c) i value is 1 and j value is undefined
d) i and j value are undefined
View Answer

Answer: d
Explanation: Bitwise OR are NOT strictly evaluated from left-to-right. Similar the ‘+’ operator has two operands f() & g() and these functions f() and g() can get evaluated in any order depending on the compiler. Hence, we can’t have a fixed value for i and j.

6. What will be the output of the following C code?

```
    #include <stdio.h>
```
```
    int main()
```
```
    {
```
```
        int x = 2, y = 0;
```
```
        int z = y && (y |= 10);
```
```
        printf("%d\n", z);
```
```
        return 0;
```
```
    }
```

a) 1
b) 0
c) Undefined behaviour due to order of evaluation
d) 2
View Answer

Answer: b
Explanation: None.

7. What will be the output of the following C code?

```
    #include <stdio.h>
```
```
    int main()
```
```
    {
```
```
        int x = 2, y = 0;
```

        int z = (y++) ? 2 : y == 1 && x;

```
        printf("%d\n", z);
```
```
        return 0;
```
```
    }
```

a) 0
b) 1
c) 2
d) Undefined behaviour
View Answer

Answer: b
Explanation: None.

8. What will be the output of the following C code?

```
    #include <stdio.h>
```
```
    int main()
```
```
    {
```
```
        int x = 2, y = 0;
```
```
        int z;
```
```
        z = (y++, y);
```
```
        printf("%d\n", z);
```
```
        return 0;
```
```
    }
```

a) 0
b) 1
c) Undefined behaviour
d) Compilation error
View Answer

Answer: b
Explanation: None.

9. What will be the output of the following C code?

```
    #include <stdio.h>
```
```
    int main()
```
```
    {
```
```
        int x = 2, y = 0, l;
```
```
        int z;
```
```
        z = y = 1, l = x && y;
```
```
        printf("%d\n", l);
```
```
        return 0;
```
```
    }
```

a) 0
b) 1
c) Undefined behaviour due to order of evaluation can be different
d) Compilation error
View Answer

Answer: b
Explanation: None.

10. What will be the output of the following C code?

```
    #include <stdio.h>
```
```
    int main()
```
```
    {
```
```
        int y = 2;
```
```
        int z = y +(y = 10);
```
```
        printf("%d\n", z);
```
```
    }
```

a) 12
b) 20
c) 4
d) Either 12 or 20
View Answer

Answer: b
Explanation: None.

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