# 求三个数中最大数的 C 程序

## 示例 1：使用 if 语句

``````#include <stdio.h>
int main() {
double n1, n2, n3;
printf("Enter three different numbers: ");
scanf("%lf %lf %lf", &n1, &n2, &n3);

// if n1 is greater than both n2 and n3, n1 is the largest
if (n1 >= n2 && n1 >= n3)
printf("%.2f is the largest number.", n1);

// if n2 is greater than both n1 and n3, n2 is the largest
if (n2 >= n1 && n2 >= n3)
printf("%.2f is the largest number.", n2);

// if n3 is greater than both n1 and n2, n3 is the largest
if (n3 >= n1 && n3 >= n2)
printf("%.2f is the largest number.", n3);

return 0;
}
``````

## 示例 2：使用 if…else

``````#include <stdio.h>
int main() {
double n1, n2, n3;
printf("Enter three numbers: ");
scanf("%lf %lf %lf", &n1, &n2, &n3);

// if n1 is greater than both n2 and n3, n1 is the largest
if (n1 >= n2 && n1 >= n3)
printf("%.2lf is the largest number.", n1);

// if n2 is greater than both n1 and n3, n2 is the largest
else if (n2 >= n1 && n2 >= n3)
printf("%.2lf is the largest number.", n2);

// if both above conditions are false, n3 is the largest
else
printf("%.2lf is the largest number.", n3);

return 0;
}
``````

## 示例 3：使用嵌套 if…else

``````#include <stdio.h>
int main() {
double n1, n2, n3;
printf("Enter three numbers: ");
scanf("%lf %lf %lf", &n1, &n2, &n3);

if (n1 >= n2) {
if (n1 >= n3)
printf("%.2lf is the largest number.", n1);
else
printf("%.2lf is the largest number.", n3);
} else {
if (n2 >= n3)
printf("%.2lf is the largest number.", n2);
else
printf("%.2lf is the largest number.", n3);
}

return 0;
}
``````

``````Enter three numbers: -4.5
3.9
5.6
5.60 is the largest number.``````