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1) Guess the output
Output of above C Program is A) 0 10.
The final value of integer variable z is 0 and variable x is 10.
Why 🤔 ?
Let’s understand logical AND operator (&&).
It(&&) returns true if both operands are true otherwise it returns false.
Initially, first operand is completely evaluated and if first operand evaluates to true i.e.(non-zero) then and then second operand will be evaluated.
In this case, the first operand is x>y and second operand is x++.
Result of first operand(x>y) is zero because value of x is 10 and y is 20. 10>20 is false.
So the second operand (x++) will not be evaluated and value of x remains same.
The result of x>y && x++ is assigned to integer variable z and which is 0(false).
Finally value of z is 0 and x is 10 so the output of above C Program is A) 0 10.
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2) Guess the output
Output of above C Program is C) 1 20.
The final value of integer variable z is 1 and variable y is 20.
Why 🤔 ?
Let’s understand logical OR operator (||).
It(||) returns true if one of the operand is true. If both operands are false then it returns false.
Initially, first operand is completely evaluated and if first operand evaluates to true i.e.(non-zero) then the second operand won’t evaluated. If first operand evaluates to false i.e.(zero) then the second operand will be evaluated.
In this case, the first operand is y>x and second operand is y++.
Result of first operand(y>x) is one(non-zero) because value of y is 20 and x is 10. 20>10 is true.
So the second operand (y++) will not be evaluated and value of y remains same.
The result of y>x && y++ is assigned to integer variable z and which is 1(true).
Finally value of z is 1 and y is 20 so the output of above C Program is C) 1 20.
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3) Guess the output
Output of above C Program is B) 20 .
The final value of integer variable x is 20 and variable a is 10.
Why 🤔 ?
Let’s understand the precedence order of operators in C .
1) ++ or — (Postfix)
2) ++ or — (Prefix)
3) * , / , %
4) +, –
Precedence order of Postfix operator is more so a– has higher precedence. The statement a-- + ++a will execute from left to right.
Post decrement/increment(a–/a++) means it will first assign the value and then decrement/increment it by 1.
Pre decrement/increment(–a/++a) means it will first decrement/increment the value by 1 and then assign it.
That’s why the output of above C Code is 20.
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4) Guess the output
Output of above C Program is C) 0 .
The final value of integer variable x is 0 and variable a is 11.
Why 🤔 ?
Let’s understand the precedence order of operators in C .
1) ++ or — (Postfix)
2) ++ or — (Prefix)
3) * , / , %
4) +,-
We know the simple rules of mathematics
a – + a = a – a
a + – a = a – a
So a - + ++a becomes a - ++a .
Here precedence of ++a is higher and statement will execute from right to left.
The statement will look like thisx = 11 - 11 (a – ++a)x = 0
Final value of x is 0 and a is 11.
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5) Guess the output
Output of the above C Program is C) 2.
Value of variable m is 1 initially. And we never call the f1() function in the main() function then how the value of variable m becomes 2.
Here is the answer.
__attribute__((constructor)) is used with a function, which executes before main() function i.e. at the start of the program.
So the function f1() is called before main() and the final value of m is 2.
Click here for the more info about __attribute__((constructor)).
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Click here to view Guess The Output series 5.
