第7次上机作业参考答案.doc

第七次上机练习参考答案1. 编写一个square(int x)函数，计算一个整数的平方，然后调用该函数计算并打印110的平方。#include int square(int x)return x * x;int main()int i;for (i = 1; i = 10; i+)printf(%d , square(i);return 0;2. 编写一个函数printChars(int n, char t)，打印n个连续的字符t，比如printChars(5, a)将会输出aaaaa。void printChars(int n, char t)int i;for (i = 0; i n; i+)printf(%c, t);3. 编写函数distance(float x1, float y1, float x2, float y2)，计算两点(x1, y1)和(x2, y2)之间的距离，返回值使用float类型。#include float distance(float x1, float y1, float x2, float y2)return sqrt(x2-x1)*(x2-x1)+(y2-y1)*(y2-y1) );4. 写一个函数判断一个整数是否为素数，并利用该函数输出1200之间所有的素数。#include #include bool isPrime(int n)if (n 2)return false;int i;for (i = 2; i = sqrt(double)n); i+)if (n % i = 0)return false;return true;int main()int i;for (i = 1; i = 200; i+)if (isPrime(i)printf(%d , i);return 0;5. 一个整数的所有因子（包括1，但不包括本身）之和等于该数，则该数称为完数。例如6是一个完数，因为6=1+2+3。编写一个isPerfectnum函数，判断number是否为完数。利用该函数判断并打印11000之间的所有完数。#include bool isPerfectnum(int n)int i;int sum = 0;for (i = 1; i n; i+)if (n % i = 0)sum+=i;if (sum = n)return true;elsereturn false;int main()int i;for (i = 1; i = 1000; i+)if (isPerfectnum(i)printf(%d , i);return 0;6. 编写递归函数，把输入的一个整数转换成二进制数输出。void printBinary(int n)if (n 2)printf(%d, n);return;printBinary(n/2);printf(%d, n % 2);7. 编写递归函数对数组元素求和。int getSum(int array, int n)if (n = 1)return array0;return arrayn-1 + getSum(array, n - 1);11.某班有5名同学选修4门课。要求把成绩数组定义为全局变量。编写函数实现以下功能：1）输入所有成绩。2）计算每名同学不及格的课程数。3）统计每门课程的及格率。4）以二维方式输出所有成绩。/*全局变量实现方法*/#include int grade54;void inputGrade()int i, j;for (i = 0; i 5; i+)for (j = 0; j 4; j+)scanf(%d, &gradeij);void failNum()int i, j, count;for (i = 0; i 5; i+)count = 0;for (j = 0; j 4; j+)if (gradeij 60)count+;printf(Studnet %d fails %d courses.n, i, count);void passRate()int i, j, count;for (j = 0; j 4; j+)count = 0;for (i = 0; i = 60)count+;printf(The passing rate of course %d is %.2f.n, j, count/5.0);void outputGrade()int i, j;for (i = 0; i 5; i+)for (j = 0; j 4; j+)printf(%d , gradeij);printf(n);int main()inputGrade();failNum();passRate();outputGrade();return 0;/*非全局变量实现方法*/#include void inputGrade(int grade54)int i, j;for (i = 0; i 5; i+)for (j = 0; j 4; j+)scanf(%d, &gradeij);void failNum(int grade54)int i, j, count;for (i = 0; i 5; i+)count = 0;for (j = 0; j 4; j+)if (gradeij 60)count+;printf(Studnet %d fails %d courses.n, i, count);void passRate(int grade54)int i, j, count;for (j = 0; j 4; j+)count = 0;for (i = 0; i = 60)count+;printf(The passing rate of course %d is %.2f.n, j, count/5.0);void outputGrade(int grade54)int i, j;for (i = 0; i 5; i+)for (j = 0; j 4; j