# C 程序：查找三個數字中最大的數字 > 原文： [https://www.programiz.com/c-programming/examples/largest-number-three](https://www.programiz.com/c-programming/examples/largest-number-three) #### 在此示例中，您將學習在用戶輸入的三個數字中找到最大的數字。 要理解此示例，您應該了解以下 [C 編程](/c-programming "C tutorial")主題： * [C 編程運算符](/c-programming/c-operators) * [C `if...else`語句](/c-programming/c-if-else-statement) * * * * * * ## 示例 1：使用`if`語句 ```c #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`階梯 ```c #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 n1 is greater than both n2 and n3, n1 is the largest else if (n2 >= n1 && n2 >= n3) printf("%.2lf is the largest number.", n2); // if both above conditions are false, m3 is the largest else printf("%.2lf is the largest number.", n3); return 0; } ``` * * * ## 示例 3：使用嵌套`if...else` ```c #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; } ``` * * * 上面所有這些程序的輸出將相同。 ```c Enter three numbers: -4.5 3.9 5.6 5.60 is the largest number. ```