C/Language Basics/If
Содержание
- 1 A simple example of the if statement
- 2 Block if else statement
- 3 if command
- 4 If else
- 5 If else if and else
- 6 If else statement inside a for loop
- 7 IF statement 3
- 8 If statement for different choice
- 9 If statement inside for loop
- 10 More if else
- 11 More statement in if else
- 12 Move more statements into if and else
- 13 Use calculation in if statement
- 14 Use if else
- 15 Use int as if condition
- 16 Use result as the if condition
- 17 Use statement inside if else
- 18 Use two if statements
- 19 Use user input as the if condition
- 20 Using ifs to decide on a discount
A simple example of the if statement
<source lang="cpp">
- include <stdio.h>
void main() {
int number = 0;
printf("\nEnter an integer between 1 and 10: ");
scanf("%d",&number);
if (number > 7)
printf("You entered %d which is greater than 7\n", number);
if (number < 3)
printf("You entered %d which is less than 3\n", number);
}
</source>
Block if else statement
<source lang="cpp">
- include <stdio.h>
int main(void) {
int answer, i;
int again;
for(i = 1; i < 11; i++) {
printf("What is %d + %d? ", i, i);
scanf("%d", &answer);
if(answer == i + i)
printf("Right!\n");
else {
printf("Wrong\n");
printf("Try again.\n ");
printf("\nWhat is %d + %d? ", i, i);
scanf("%d", &answer);
/* nested if */
if(answer == i + i)
printf("Right!\n");
else
printf("Wrong, the answer = %d\n", i + i);
}
}
return 0;
}
</source>
if command
<source lang="cpp">
- include <stdio.h>
int main() {
float cost, tax, luxury, total;
luxury = 0.0;
printf("Enter the cost: ");
scanf("%f", &cost);
tax = cost * 0.06;
if( cost > 40000.0)
luxury = cost * 0.005;
total = cost + tax + luxury;
printf("the total cost is %0.2f", total);
}
</source>
If else
<source lang="cpp">
- include <stdio.h>
- include <stdlib.h>
int main(void) {
int magic; /* magic number */
int guess; /* user"s guess */
magic = rand(); /* generate the magic number */
printf("Guess the magic number: ");
scanf("%d", &guess);
if(guess == magic) printf("** Right **");
else printf("Wrong");
return 0;
}
</source>
If else if and else
<source lang="cpp"> /* Magic number program #4. */
- include <stdio.h>
- include <stdlib.h>
int main(void) {
int magic; /* magic number */
int guess; /* user"s guess */
magic = rand(); /* generate the magic number */
printf("Guess the magic number: ");
scanf("%d", &guess);
if(guess == magic) {
printf("** Right ** ");
printf("%d is the magic number", magic);
}
else if(guess > magic)
printf("Wrong, too high");
else printf("Wrong, too low");
return 0;
}
</source>
If else statement inside a for loop
<source lang="cpp">
- include <stdio.h>
int main(void) {
int answer, i;
int right, wrong;
right = 0;
wrong = 0;
for( i = 1; i < 11; i = i + 1) {
printf("What is %d + %d? ", i, i);
scanf("%d", &answer);
if(answer == i + i) {
printf("Right! ");
right++;
}
else {
printf("Sorry, you"re wrong. ");
printf("The answer is %d. ", i + i);
wrong++;
}
}
printf("You got %d right and %d wrong.", right, wrong);
return 0;
}
</source>
IF statement 3
<source lang="cpp">
- include <stdio.h>
main() {
int i,j,big; //variable
scanf("%d%d",&i,&j);
big = i;
if(big < j) {
big = j;
}
printf("bigger one is %d \n",big);
if(i < j) {
big = j;
} else {
big = i;
}
printf("bigger one (using else) is %d \n",big);
}
</source>
If statement for different choice
<source lang="cpp">
- include <stdio.h>
int main(void) {
float num;
int choice;
printf("1: Change Feet to Meters, 2: Change Meters to Feet. ");
printf("Choice: ");
scanf("%d", &choice);
if(choice == 1) {
printf("Enter number of feet: ");
scanf("%f", &num);
printf("Meters: %f", num / 3.28);
} else {
printf("Enter number of meters: ");
scanf("%f", &num);
printf("Feet: %f", num * 3.28);
}
return 0;
}
</source>
If statement inside for loop
<source lang="cpp">
- include <stdio.h>
- include <conio.h>
int main(void) {
int i;
char ch;
/* display all numbers which are multiples of 6 */
for(i = 5; i < 10000; i++) {
if(!( i % 6 )) {
printf("%d, more number? (Y/N)", i);
ch = getche();
if(ch == "N")
break; /* stop the loop */
printf("\n");
}
}
return 0;
}
</source>
More if else
<source lang="cpp">
- include <stdio.h>
int main(void) {
int a, b;
char ch;
printf("Choice:\n");
printf("(A) Add, (S) Subtract, (M) Multiply, or (D) Divide?\n");
ch = getchar();
printf("\n");
printf("Enter a: ");
scanf("%d", &a);
printf("Enter b: ");
scanf("%d", &b);
if(ch=="A") printf("%d", a+b);
else if(ch=="S") printf("%d", a-b);
else if(ch=="M") printf("%d", a*b);
else if(ch=="D" && b!=0) printf("%d", a/b);
return 0;
}
</source>
More statement in if else
<source lang="cpp"> /* Magic number program #3. */
- include <stdio.h>
- include <stdlib.h>
int main(void) {
int magic; /* magic number */
int guess; /* user"s guess */
magic = rand(); /* get a random number */
printf("Guess the magic number: ");
scanf("%d", &guess);
if (guess == magic) {
printf("** Right **");
printf(" %d is the magic number\n", magic);
}
else {
printf("Wrong, ");
if(guess > magic) printf("too high\n"); /* nested if */
else printf("too low\n");
}
return 0;
}
</source>
Move more statements into if and else
<source lang="cpp">
- include <stdio.h>
int main(void) {
int a, b, op;
printf("Enter 0 to add, 1 to subtract: ");
scanf("%d", &op);
if(op == 0) { /* add */
printf("Enter first number: ");
scanf("%d", &a);
printf("Enter second number: ");
scanf("%d", &b);
printf("%d", a+b);
}
else { /* subtract */
printf("Enter first number: ");
scanf("%d", &a);
printf("Enter second number: ");
scanf("%d", &b);
printf("%d", a-b);
}
return 0;
}
</source>
Use calculation in if statement
<source lang="cpp">
- include <stdio.h>
int main(void) {
int answer;
printf("What is 110 + 14? ");
scanf("%d", &answer);
if(answer == 110+14)
printf("Right!");
else {
printf("Wrong. ");
printf("The answer is 124.");
}
return 0;
}
</source>
Use if else
<source lang="cpp">
- include <stdio.h>
int main(void) {
int a, b, op;
printf("Enter first number: ");
scanf("%d", &a);
printf("Enter second number: ");
scanf("%d", &b);
printf("Enter 0 to add, 1 to multiply: ");
scanf("%d", &op);
if(op == 0)
printf("%d", a + b );
else
printf("%d", a * b );
return 0;
}
</source>
Use int as if condition
<source lang="cpp">
- include <stdio.h>
int main(void) {
int num;
printf("Enter an integer: ");
scanf("%d", &num);
if(num < 0)
printf("Number is negative.");
else
printf("Number is non-negative.");
return 0;
}
</source>
Use result as the if condition
<source lang="cpp">
- include <stdio.h>
int main(void) {
int answer;
printf("What is 110 + 14? ");
scanf("%d", &answer);
if(answer == 110+14)
printf("Right!");
return 0;
}
</source>
Use statement inside if else
<source lang="cpp">
- include <stdio.h>
int main(void) {
int i;
printf("Enter a number: ");
scanf("%d", &i);
if( ( i % 2) == 0)
printf("Even");
else
printf("Odd");
return 0;
}
</source>
Use two if statements
<source lang="cpp">
- include <stdio.h>
int main(void) {
int num;
printf("Enter an integer: ");
scanf("%d", &num);
if(num < 0)
printf("num is negative.");
if(num > -1)
printf("num is non-negative.");
return 0;
}
</source>
Use user input as the if condition
<source lang="cpp">
- include <stdio.h>
int main(void) {
float num;
int choice;
printf(" Meter or Feet: ");
scanf("%f", &num);
printf("1: Feet to Meters, 2: Meters to Feet. ");
printf("Enter choice: ");
scanf("%d", &choice);
if(choice == 1)
printf("%f", num / 3.28);
if(choice == 2)
printf("%f", num * 3.28);
return 0;
}
</source>
Using ifs to decide on a discount
<source lang="cpp">
- include <stdio.h>
void main() {
const double price = 3.50; /* price*/
int quantity = 0;
printf("Enter the number that you want to buy:"); /* Prompt message */
scanf(" %d", &quantity); /* Read the input */
/* Test for order quantity qualifying for a discount */
if( quantity>20) /* 5% discount */
printf("The price for %d is $%.2f\n", quantity, quantity * price * 0.95);
else
/* No discount */
printf("The price for %d is $%.2f\n", quantity, quantity * price);
}
</source>
