C Programming Basics: Operators

Type Conversion and Data Types

• When a char variable is added to an integer variable, the char is first converted to its corresponding integer value before the addition takes place.
• The output will be 3.5. The (int) a cast converts the double a to an integer (2) before adding 1.5
• A false statement regarding type conversion is that type conversion always happens implicitly, which is incorrect, as explicit type conversion is also possible using casting.
• The result of dividing an integer by a double will be a double.
• The result will be 1.5, as the integer a (3) is implicitly converted to a double before division by the double b (2).

Logical Operators and Operators Precedence

• The expression 5 < b < 10 with b as 20 would evaluate to false. The operators are evaluated from left to right in this scenario. First, 5 < 20 evaluates to true which is equal to 1. Then 1 < 10 evaluates to true, resulting in the final output of true.
• The logical AND (&&) operator would result in true because both expressions (a < b) and (b < c) are true given the provided values of a, b, and c.
• The pre-increment operator increments the variable before its value is used in the expression. The final value of y will be 3.
• The >= operator (greater than or equal to) will evaluate to true because the (a + 10) is 11, which is indeed greater than or equal to d, which is 100. So, the output will be true.
• The expression !(c < d) will produce false. The inner c < d is true as 50 is less than 100 but the logical negation operator ! negates this result resulting in false.
• In the expression d || b && a, the operator precedence is as follows: && (logical AND) has higher precedence than || (logical OR). So, the expression will be evaluated as d || (b && a).
• A post-increment operation increments the variable after its value is used in the expression. So, the original value is used in the expression.
• The output of result = (a – b) && 1 in C will be 0 (which is considered false). The (a – b) evaluates to -19, which is false because it's a non-zero negative number. Therefore, the expression (a-b) && 1 becomes 0 && 1 which evaluates to 0.
• The final value of y after result = y++ will be 3. The post-increment operator increments the value of y after it has been used in the expression 'result = y++'. Therefore, the value of y will be 3, and result will contain 2, the original value of y.
• The --x (pre-decrement) operator decrements the value of x before it is used in the expression, while x-- (post-decrement) operator decrements the value of x after it has been used in the expression.
• The increment and decrement operators have higher precedence than arithmetic operators. They are usually evaluated before arithmetic operations.
• The & (reference operator) is used to obtain the memory address of a variable. It returns the memory address of the variable.

Understanding Pointers, Operators, and Expressions

• The final output of printf(“Value of y-- is %d ”,result); will be "Value of y-- is 2". This is because the postfix -- decrement operator decrements the value of y after it is used in the expression result = y--. Therefore, the value of y will be 1 after the expression is executed, but the value of result will be 2, which is printed.
• The ternary operator is a shorthand way to write an if-else statement in C. It takes three operands and returns one of two values depending on the result of the first operand.
• y will be incremented to 4. Since ++ is a pre-increment operator, it increments the value of y before assigning it to x.
• The sizeof operator returns the number of bytes occupied by a data type or a variable.
• The output will be 20. Dereferencing a pointer (*ptr) accesses the value stored at the memory location pointed to by the pointer. Since ptr is pointing to a (20), *ptr will give the value of a, which is 20.
• The unary negation operator (!) has the highest precedence in C.
• The sizeof operator is used to calculate the size in bytes of a data type or a variable.
• When the operation *ptr = 30 is performed, the value at the memory location pointed to by the pointer ptr is changed to 30.
• Assignment operators like =, +=, and -= in C have right-to-left associativity.
• The output will be Value pointed by pointer ptr is 4\n. This is because ptr is pointing to memory location of a which has value 4.
• The order of operations for *, /, and + is: * and / have the same priority and are evaluated from left to right. + has lower priority than * and /.
• The dereference operator (*) returns the value that is stored at the memory location pointed to by the pointer.
• The output will be "The value of x is 15\n". The instruction x = x + 5 increases the value of x by 5.
• The new value of x will be 8. The -= operator subtracts the right operand from the left operand and assigns the result to the left operand.
• A valid use of relational operators in C would be x > y or x <= y, which compares the values of variables x and y using the relational operators > (greater than) and <= (less than or equal to).
• The statement x *= 2 multiplies the value of x by 2 and assigns the result back to x.
• The result of the comparison 5 != 5 will be false. The != operator checks if the two operands are not equal.
• In C, the operator * (multiplication) has higher precedence than the assignment operator =.
• The output of printf("The value of a is %d\n", a); will be "The value of a is 10\n", as a has been set to 10.
• In C, 1 (or any non-zero value) represents true in logical operations.