实验4

目的：1. 掌握函数定义的方法，函数的调用，实参形参，函数返回值的概念； 2. 掌握函数的嵌套调用，递归调用；

3. 掌握变量的作用范围,体会模块化程序设计思路。

Objectives: 1. To understand the methods for defining function, invoking function,

and the concept of real parameter, formatted parameter and return statement;

2. To master the nesting invoking and the recursion invoking;

3. To master the scope of the variable, and to experience the concept of modular programming.

1.自定义函数，求数的平方

To design a customization function that enables to calculate the square of the given value.

2. 用函数嵌套调用形式编写程序，计算1!+2!+3!+……+n!，要求n的值要由键盘

输入

To calculate 1!+2!+3!+……+n! by nesting invoking, and the value of n should be acquired from keyboard.

3.

To calculate mn by recursion invoking, and the values of m and n should be acquired from keyboard. 4.

用递归方法计算m，要求m和n的值都由键盘输入

n

仔细阅读程序, 注意变量的作用域, 存储类别, 若输入 1, 2, 3, 4, 5；分析程序的运行结

果。

To read the codes to analyze the scope of the variable and the storage style; if 1, 2, 3, 4, 5 are

input, please predict the result of the program.

void f1（x, y）

{auto int i; 

static int j; /*调用完, j值保留*/ printf（″i=%5d, j=%5d\\n″, i, j）;  i=x+y;  j+=x+y; 

printf（″i=%5d, j=%5d\\n″, i, j）;  printf（″x=%5d, y=%5d\\n″, x, y）;  }

static int k, l, m; /*在本程序文件内使用*/ void f2（a, b, c） int a, b, c;  { k=a+b+c; 

l=a*b*c; 

m=k+l; 

printf（″a=%5d, b=%5d, c=%5d\\n″, a, b, c）;  printf（″k=%5d, l=%5d, m=%5d\\n″, k, l, m）; }

main( )

{int d, e, f, g, h; 

int i, j, x, y, a, b, c; 

printf（″please input d, e, f, g, h: ″）; 

scanf（″%d, %d, %d, %d, %d″, &d, &e, &f, &g, &h）;  printf（″the first invoking f1( )\\n″）;  f1（d, e）;

printf（″i=%5d, j=%5d\\n″, i, j）;  printf（″x=%5d, y=%5d\\n″, x, y）;  printf（″d=%5d, e=%5d\\n″, d, e）;  printf（″the second invoking f1( )\\n″）;  f1（d, e）; 

printf（″i=%5d, j=%5d\\n″, i, j）;  printf（″to invoke function f2( )\\n″）;  f2（f, g, h）; 

printf（″k=%5d, l=%5d, m=%5d\\n″, k, l, m）;  printf（″a=%5d, b=%5d, c=%5d\\n″, a, b, c）;  printf（″f=%5d, g=%5d, h=%5d\\n″, f, g, h）;  }

5.程序体验：通用面积计算程序。  (1) 正方形 (2) 长方形 (3) 圆 

(4) 三角形 (5) 梯形 (6) 平行四边形

To experience the codes: the program for calculating general areas which contain square, rectangle, circle, triangle, trapezium, and parallelogram

main( ) {char ch; void zs( ); void cs( );  void ys( );  void ss( );  void ds( );  void ps( );  void tc( );  while （1）

{

printf（″ The codes for calculating general areas \\n″）; 

printf（″Z refers to square; C refers to rectangle; Y refers to circle \\n″）; 

printf（″S refers to triangle; D refers to trapezium; P refers to parallelogram \\n″）;  printf（″Q for quit \\n″）; 

printf（″please select the operation（Z/C/Y/S/D/P/Q）: ″）;  ch=getchar( );  switch （ch）

{ case ′z′: 

case ′Z′: zs( ); break;  case ′c′: 

case ′C′: cs( ); break;  case ′y′: 

case ′Y′: ys( ); break;  case ′s′: 

case ′S′: ss( ); break;  case ′d′: 

case ′D′: ds( ); break;  case ′p′: 

case ′P′: ps( ); break;  case ′q′: 

case ′Q′: tc( ); break; 

default: printf（″Wrong choice！″）; } } } 

void zs( ) {float a;  float s; 

printf（″please input the side length of the square: ″）; scanf（″%f″, &a）;  s=a*a; 

printf（″the area of the square =%7.3f\\n″, s）;  }



void cs( ) {float a, b;  float s; 

printf（″please input the length and the width of rectangle: ″）;  scanf（″%f, %f″, &a, &b）;  s=a*b; 

printf（″the area of the rectangle =%7.3f\\n″, s）;  }



＃define PI 3.14159 void ys( )

{float r; 

float s; 

printf（″please input the radius of the circle ″）;  scanf（″%f″, &r）;  s=PI*r*r; 

printf（″the area of the circle =%7.3f\\n″, s）;  }



void ss( ) {float a, b, c;  float l;  int flag; 

float s; 

printf（″please input the each side of the triangle: ″）;  scanf（″%f, %f, %f″, &a, &b, &c）;  flag=（a+b>c）&&（b+c>a）&&（c+a>b）; if （flag）

{l=0.5*(a+b+c); 

s=sqrt（l*（l-a）*（l-b）*（l-c））; 

printf（″the area of the triangle =%7.3f\\n″, s）;  }

else printf（″the sides are not able to form a triangle！\\n″）;  } 

void ds( ) {float a, b, h;  float s; 

printf(“please input the top edge, bottom edge, and the height of the trapezium respectively: “); scanf（″%f, %f, %f″, &a, &b, &h）;  s= (a+b)*h*0.5; 

printf（″the area of the trapezium =%7.3f\\n″, s）;  }

void ps( ) {float a , h; 

float s; 

printf（″please input the bottom edge and the height of the parallelogram: ″）;  scanf（″%f, %f″, &a, &h）; 

s= a*h; 

printf（″the area of the parallelogram =%7.3f\\n″, s）;  }

void tc( )

{printf（″To quit the program！″）;  exit（0）;  }

参考答案：The reference answers

1.

＃include 

long square (long x)

{ long xsquare; xsquare=x*x;

return xsquare;  }  void main() 

{ long innum, result; 

printf(＂Input an integer: ＂);  scanf(＂%ld＂, &innum);  result=square (innum); 

printf(＂＼nThe square number of %ld is %ld＂, innum, result); }

2.int power (int n) {int f;

if(n= =1) f=1;

else f=power(n-1)*n; return(f);}

int sum (int n) {int i, s,y; s=0;

for (i=1;i{y=power(i); s+=y;} return(s); }

main()

{int sum1, n;

scanf(“%d”, &n); sum1=sum(n);

printf(“%d\\n”, sum1);}

3.

long mn（int m, int n）

{long j; 

if （n>0） j=m*mn（m, n-1）; else j=1;  return（j）; } main()

{ int m,n;

long f;

scanf(“%d,%d”, &m,&n); f=mn(m,n); printf(“%ld”, f); }

4.运行结果: 

The first invoking f1( )

i= 34（random value）, j= 0  i= 3, j= 3  x= 1, y= 2

i= 34（random value）, j= 1985 （random value）  x= -19（random value）, y= 2340（random value） d= 1, e= 2 the second invoking f1( )

i= 34（random value）, j= 3  i= 3, j= 6  x= 1, y= 2

i= 34（random value）, j= 1985 （random value）  to invoke function f2( ) 

a= 3, b= 4, c= 5 k= 12, l = 60, m= 72 k= 12, l = 60, m= 72

a= 13（random value）, b= 124（random value）, c= 2525（random value） f= 3, g= 4, h= 5