If statement in while loop not working - c

Question

For the past 3 days, I have been having program trying to fix this code. Can someone here please help. The program doesn't print the last statement if a negative number is imputed. If a negative number is imputed, instead of printing "Terminating the program...", it jumps to print "Enter the first number:" before quitting.
int main(void)
{
int choose, number1, number2, total_hold;
do
{
printf("\n");
printf("1: sum of two numbers \n");
printf("2: difference of two numbers\n");
printf("3: product of two numbers\n");
printf("<0:terminate the program\n");
printf("Select calculation:");
scanf("%d", &choose);
printf("Enter the first number:");
scanf("%d", &number1);
printf("Enter the second number:");
scanf("%d", &number2);
if (choose == 1)
{
total_hold = sumOfNumbers(number1, number2);
displayS(number1, number2, total_hold);
}
else if (choose == 2)
{
total_hold = differenceOfNumbers(number1, number2);
displayD(number1, number2, total_hold);
}
else if (choose == 3)
{
total_hold = MultiplicationOfNumbers(number1, number2);
displayM(number1, number2, total_hold);
}
else if (choose < 0)
{
printf("Terminating the program...");
break;
}
}
while (choose > 0);
return 0;
}

Answer 1

Place this:
if (choose < 0)
{
printf("Terminating the program...");
break;
}
Immediately after you scanf("%d", &choose).
In addition to that, you may as well change while (choose > 0) to while (1).

Answer 2

You are using a
do{
statement 1;
statement 2;
...
...
statement n;
}while(condition);
Hence in do-while loop all the statement are executed at-least once and then the condition is checked.
Better to use while loop instead of do-while

Answer 3

You're executing three scanf instructions before ANY if statement. If you want to check if choose variable is lower than 0 you can do it BEFORE the other two scanf calls like this
int main(void)
{
int choose, number1, number2, total_hold;
do
{
printf("\n");
printf("1: sum of two numbers \n");
printf("2: difference of two numbers\n");
printf("3: product of two numbers\n");
printf("<0:terminate the program\n");
printf("Select calculation:");
scanf("%d", &choose);
if (choose < 0)
{
printf("Terminating the program...");
break;
}
printf("Enter the first number:");
scanf("%d", &number1);
printf("Enter the second number:");
scanf("%d", &number2);
if (choose == 1)
{
total_hold = sumOfNumbers(number1, number2);
displayS(number1, number2, total_hold);
}
else if (choose == 2)
{
total_hold = differenceOfNumbers(number1, number2);
displayD(number1, number2, total_hold);
}
else if (choose == 3)
{
total_hold = MultiplicationOfNumbers(number1, number2);
displayM(number1, number2, total_hold);
}
}
while (choose > 0);
return 0;
}

Answer 4

Statements
printf("Enter the first number:");
scanf("%d", &number1);
printf("Enter the second number:");
scanf("%d", &number2);
are executed indpendently of the value entered in varaible choose because the last is tested after these statements.
The more correct design of the program could look like (without testing)
#include <stdio.h>
int main(void)
{
while ( 1 )
{
enum { Exit = 0, Addition = 1, Difference = 2, Multiplication = 3 };
unsigned int choose;
int number1, number2, total_hold;
printf( "\n" );
printf( "%d: sum of two numbers \n", Addition );
printf( "%d: difference of two numbers\n", Difference );
printf( "%d: product of two numbers\n", Multiplication );
printf( "%d: terminate the program\n", Exit );
printf( "Select calculation:" );
scanf( "%u", &choose );
if ( choose == Exit )
{
printf( "Terminating the program..." );
break;
}
if ( choose <= Multiplication )
{
printf( "Enter the first number:" );
scanf( "%d", &number1 );
printf( "Enter the second number:" );
scanf( "%d", &number2 );
}
switch ( choose )
{
case Addition: {
total_hold = sumOfNumbers(number1, number2);
displayS(number1, number2, total_hold);
break;
case Difference:
total_hold = differenceOfNumbers(number1, number2);
displayD(number1, number2, total_hold);
break;
case Multiplication:
total_hold = MultiplicationOfNumbers(number1, number2);
displayM(number1, number2, total_hold);
break;
default:
printf("Invalid selection. Try again.\n");
break;
}
}
return 0;
}