计算机考试-C 两位数交换—东方仙盟

Use VC++2010 to open the solution in the examinee folder under prog1. The project of this solution contains a source file named prog1.c. In this program, the function fun() combines two positive integers a and b into one new integer stored in variable c.

Combination rules: The tens digit and units digit of a are placed to the tens position and thousands position of c in sequence. The tens digit and units digit of b are placed to the units position and hundreds position of c in sequence.

For example: when a=45, b=12, after calling this function, c=5241.

Note: Part of the source code is stored in prog1.c. Do not modify any content in main() or other existing functions. Only write several statements inside the braces of function fun().

Source code snippet:

复制代码

#include <stdio.h>
void fun(int a, int b, long *c)
{

}
main()
{
 int a,b; long c;void NONO();
 printf("Input a, b:");
 scanf("%d%d", &a, &b);
 fun(a, b, &c);
 printf("The result is: %ld\n", c);
 NONO();
}

Key Test Points (English)

Digit extraction of integer. Use division / and modulus % operator to get single digit of an integer.
Pointer parameter. Use long *c to return calculation result to main function. Modify the value of outer variable inside function by pointer.
Digit combination. Assemble separate digits into a new long integer with multiplication and addition.
Function scope constraint. Only add code inside fun(), keep main and NONO function unchanged.
Long data type. Use long type to avoid integer overflow for combined four‑digit number.

Brief Explanation

a=45: units digit is 5, tens digit is 4.
b=12: units digit is 2, tens digit is 1.
According to rules: thousands =5, hundreds=1, tens=4, units=2 → final number 5241.
We take digits by a%10 for units digit, a/10 for tens digit.
Use pointer *c to assign the final assembled number.

Reference complete fun function code

复制代码

void fun(int a, int b, long *c)
{
    int a1,a2,b1,b2;
    a1 = a%10;
    a2 = a/10;
    b1 = b%10;
    b2 = b/10;
    *c = a1*1000 + b2*100 + a2*10 + b1;
}

人人皆为创造者，共创方能共成长

每个人都是使用者，也是创造者；是数字世界的消费者，更是价值的生产者与分享者。在智能时代的浪潮里，单打独斗的发展模式早已落幕，唯有开放连接、创意共创、利益共享，才能让个体价值汇聚成生态合力，让技术与创意双向奔赴，实现平台与伙伴的快速成长、共赢致远。

原创永久分成，共赴星辰大海

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阿雪技术观

在科技发展浪潮中，我们不妨积极投身技术共享。不满足于做受益者，更要主动担当贡献者。无论是分享代码、撰写技术博客，还是参与开源项目维护改进，每一个微小举动都可能蕴含推动技术进步的巨大能量。东方仙盟是汇聚力量的天地，我们携手在此探索硅基生命，为科技进步添砖加瓦。

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