Question

Can you help fix this error

lvalue required as left operand of assignment
if(isEven(input)=1)

int main()
{
int input;
input == 0;

printf("Please input an integer: ");
scanf("%d", &input);

if(isOdd(input)=1)
{
printf("%d is an odd number!\n", input);
}
if(isEven(input)=1)
{
printf("%d is an even number!\n", input);
}

return 0;
}

Answer 1

The statement that we write inside if must be a statement whose answer can be derived as true or false. Generally conditional statements are used inside if.

lets take few examples here:

1) consider x=1 and y=1

so in order to check whether the value of x and y are equal or not we will write as:

if(x==y) -> here == is used for comparison whose result will be true

2) consider x=2 and y=4

and we need to check whether x is greater than y then we use the following statement

if(x>y) -> since x=2 and y=4, means x is not greater than y so the answer to the statement is false.

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In your program:

if(isEven(input)=1)

The above statement is using = means that assign 1 to the the function isEven. These statement is incorrect as we cannot assign a number to a function and if needs the result as true or false which requires comparison.

That is why you are getting the lvalue required error.

so instead of if(isEven(input)=1)

we have to use if(isEven(input)==1)

and instead of if(isOdd(input)=1)

we have to use if(isOdd(input)==1)

____________________________________________________________________________________________

I have executed the program for you so please check the program:

#include<stdio.h>

int isEven(int input)                                       // isEven() to check whether the number is even or not
{
   if(input%2==0)                                           // if number modulus 2 is equals to 0 then return 1 else return 0
   return 1;
   else
   return 0;
}

int isOdd(int input)                                       // isOdd() to check whether the number is odd or not
{
   if(input%2==1)                                           // if number modulus 2 is equals to 1 then return 1 else return 0
   return 1;
   else
   return 0;
}

int main()
{
int input;
input == 0;

printf("Please input an integer: ");                       // take the number from user in input variable
scanf("%d", &input);

if(isOdd(input)==1)                                           // call isOdd() and if return value is 1 then print that the number is odd
{
printf("%d is an odd number!\n", input);
}
if(isEven(input)==1)                                       // call isEven() and if the return value is 1 then print the number is even
{
printf("%d is an even number!\n", input);
}

return 0;
}

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Output: