第7章函数
例7.1
#include
int main()
{
void print_star();
void print_message();
print_star();
print_message();
print_star();
return 0;
}
void print_star()
{
printf("***********************************\n"); }
void print_message()
{
printf("How do you do!\n");
}
例7.2
int max(int x,int y)
{
int z;
z=x>y?x:y;
return(z);
}
#include
int main()
{
int max(int x,int y);
int a,b,c;
printf("please enter two integer number:");
scanf("%d,%d",&a,&b);
c=max(a,b);
printf("max is %d\n",c);
return 0;
}
例7.3
#include
int main()
{
int max(float x,float y);
float a,b;
int c;
printf("please enter two integer number:");
scanf("%f,%f",&a,&b);
c=max(a,b);
printf("max is %d\n",c);
return 0;
}
int max(float x,float y)
{
float z;
z=x>y?x:y;
return(z);
}
例7.4
#include
int main()
{
float add(float x,float y);
float a,b,c;
printf("please enter a and b:");
scanf("%f,%f",&a,&b);
c=add(a,b);
printf("sum is %f\n",c);
return 0;
}
float add(float x,float y)
{
float z;
z=x+y;
return(z);
}
例7.5
#include
int main()
{
int max4(int a,int b,int c,int d);
int a,b,c,d,max;
printf("please enter 4 interger number:");
scanf("%d %d %d %d",&a,&b,&c,&d);
max=max4(a,b,c,d);
printf("max=%d\n",max);
return 0;
}
int max4(int a,int b,int c,int d)
{
int max2(int a,int b);
int m;
m=max2(a,b);
m=max2(m,c);
m=max2(m,d);
return(m);
}
int max2(int a,int b)
{
if(a>=b) return a;
else return b;
}
#include
int main()
{
int max4(int a,int b,int c,int d);
int a,b,c,d,max;
printf("please enter 4 interger number:");
scanf("%d %d %d %d",&a,&b,&c,&d);
max=max4(a,b,c,d);
printf("max=%d\n",max);
return 0;
}
int max4(int a,int b,int c,int d)
int max2(int a,int b);
return(max2(max2(max2(a,b),c),d)); }
int max2(int a,int b)
{
return(a>b?a:b);
}
例7.6
#include
int main()
{
int age(int n);
printf("NO.5,age:%d\n",age(5));
return 0;
}
int age(int n)
{
int c;
if(n==1) c=10;
else c=age(n-1)+2;
return(c);
}
例7.7递归方法求n!
#include
int main()
{
int fac(int n);
int n,y;
printf("input a interger number:");
scanf("%d",&n);
y=fac(n);
printf("%d!=%d\n",n,y);
return 0;
}
int fac(int n)
{
int f;
if(n<0) printf("n<0,data error!");
else if(n==0||n==1) f=1;
else f=fac(n-1)*n;
return(f);
例7.8汉诺塔
#include
int main()
{
void hanoi(int n,char one,char two,char three);
int m;
printf("input the number of diskes:");
scanf("%d",&m);
printf("The step to move %d diskes:\n",m);
hanoi(m,'A','B','C');
}
void hanoi(int n,char one,char two,char three)//将N-1个盘子从一座移到另一座。
{
void move(char x,char y);//用到这个函数,提前声明
if(n==1) move(one,three);//最后一步1-3
else
{
hanoi((n-1),one,three,two);//小和尚工作n-1个盘子借用3由1搬到2
move(one,three);//老和尚工作最大盘子由1搬到3
hanoi((n-1),two,one,three);//小和尚工作n-1个盘子借用2由1搬到3,完成工作}
}
void move(char x,char y)//将一个盘子从一座移到另一座
{
printf("%c-->%c\n",x,y);
}
例7.9
#include
int main()
{
int max(int x,int y);
int a[10],m,n,i;
printf("enter 10 interger numbers:");
for(i=0;i<10;i++)
scanf("%d",&a[i]);
printf("\n");
for(i=1,m=a[0],n=0;i<10;i++)
{
if (max(m,a[i])>m)
{
m=max(m,a[i]);
n=i;
}
}
printf("The largest number is %d\nit is the %dth number.\n",m,n+1); }
int max(int x,int y)
{
return(x>y?x:y);
}
例7.10
#include
int main()
{
float average(float array[10]);
float score[10],aver;
int i;
printf("enter 10 scores:\n");
for(i=0;i<10;i++)
scanf("%f",&score[i]);
printf("\n");
aver=average(score);
printf("average score is %5.2f\n",aver);
return 0;
}
float average(float array[10])
{
int i;
float aver,sum=array[0];
for (i=1;i<10;i++)
sum=sum+array[i];
aver=sum/10;
return(aver);
}
例7.11
#include
int main()
{
float average(float array[10],int n);
float score1[5]={98.5,97,91.5,60,55};
float score2[10]={67.5,89.5,99,69.5,77,89.5,76.5,54,60,99.5};
printf("The average of class A is %6.2f\n",average(score1,5));
printf("The average of class B is %6.2f\n",average(score2,10));
return 0;
}
float average(float array[10],int n)
{
int i;
float aver,sum=array[0];
for (i=1;i sum=sum+array[i]; aver=sum/n; return(aver); } 例7.12 #include int main() { void sort(int array[],int n); int a[10],i; printf("enter array:\n"); for(i=0;i<10;i++) scanf("%d",&a[i]); sort(a,10); printf("The sorted array:\n"); for(i=0;i<10;i++) printf("%d ",a[i]); printf("\n"); return 0; } void sort(int array[],int n) { int i,j,k,t; for(i=0;i { k=i; for(j=i+1;j if(array[j] k=j; t=array[k];array[k]=array[i];array[i]=t; } } 例7.13 #include int main() { int max_value(int array[][4]); int a[3][4]={{1,3,5,7},{2,4,6,8},{15,17,34,12}}; printf("Max value is %d\n",max_value(a)); return 0; } int max_value(int array[][4]) { int i,j,max; max=array[0][0]; for(i=0;i<3;i++) for(j=0;j<4;j++) if(array[i][j]>max) max=array[i][j]; return(max); } 例7.14 #include float Max=0,Min=0; int main() { float average(float array[],int n); float ave,score[10]; int i; printf("Please enter 10 score:"); for(i=0;i<10;i++) scanf("%f",&score[i]); ave=average(score,10); printf("max =%6.2f\nmin=%6.2f\naverage=%6.2f\n",Max,Min,ave); return 0; } float average(float array[],int n) { int i; float aver,sum=array[0]; Max=Min=array[0]; for(i=1;i { if(array[i]>Max) Max=array[i]; else if(array[i] sum+=array[i]; } aver=sum/n; return(aver); } 例7.15 #include int a=3,b=5; int main() { int max(int a,int b); int a=8; printf("max=%d\n",max(a,b)); return 0; } int max(int a,int b) { int c; c=a>b?a:b; return(c); } 例7.16 #include int main() { int f(int); int a=2,i; for (i=0;i<3;i++) printf("%d\n",f(a)); return 0; } int f(int a) { auto int b=0; static c=3; b=b+1; c=c+1; return(a+b+c); } 例7.17 #include int main() { int fac(int n); int i; for (i=1;i<=5;i++) printf("%d!=%d\n",i,fac(i)); return 0; } int fac(int n) { static int f=1; f=f*n; return(f); } 例7.18 #include int main() { int max(); extern int A,B,C; printf("Please enter three interger numbers\n"); scanf("%d %d %d",&A,&B,&C); printf("max is %d\n",max()); return 0; } int A,B,C; int max() { int m; m=A>B?A:B; if(C>m)m=C; return(m); } 例7.19 file1.c #include int A; int main() { int power(int); int b=3,c,d,m; printf("enter the number a and its power m:\n"); scanf("%d,%d",&A,&m); c=A*b; printf("%d*%d=%d\n",A,b,c); d=power(m); printf("%d**%d=%d\n",A,m,d); return 0; } file2.c extern A; int power(int n) { int i,y=1; for(i=1;i<=n;i++) y*=A; return(y); } 例7.20 file1.c #include int main() { extern void enter_string(char str[]); extern void delete_string(char str[],char ch); extern void print_string(char str[]); char c,str[80]; enter_string(str); scanf("%c",&c); delete_string(str,c); print_string(str); return 0; } file2.c void enter_string(char str[80]) { gets(str); } file3.c void delete_string(char str[],char ch) { int i,j; for(i=j=0;str[i]!='\0';i++) if(str[i]!=ch) str[j++]=str[i]; str[j]='\0'; } file4.c void print_string(char str[]) { printf("%s\n",str); } 习题 1. #include int divisor(x,y) { int r; if(x { r=x; x=y; y=r; } while(r) { r=x%y; x=y; y=r; } return(x); } int multiple(int x,int y) { int z; z=x*y/divisor(x,y); return(z); } int main() { int a,b; printf("请输入两个整数a和b:"); scanf("%d,%d",&a,&b); printf("a和b的最大公约数为%d.\n",divisor(a,b)); printf("a和b的最小公倍数为%d.\n",multiple(a,b)); return 0; } 2. #include #include float d; void disc1(float a,float b,float c) { printf("方程有两不等实根:x1=%5.2f,x2=%5.2f\n",(-b+sqrt(d))/(2*a),(-b-sqrt(d))/(2*a)); } void disc2(float a,float b,float c) { printf("方程有两相等实根:x1=x2=%5.2f\n",-b/(2*a)); } void disc3(float a,float b,float c) { printf("方程有两不等实 根:x1=%5.2f+%5.2fi,x2=%5.2f-%5.2fi\n",-b/(2*a),sqrt(-d)/(2*a),-b/(2*a),sqrt(-d)/(2*a)); } int main() { float a,b,c; printf("请输入a,b,c:"); scanf("%f,%f,%f",&a,&b,&c); d=b*b-4*a*c; if(d>0) disc1(a,b,c); else if(fabs(d)<=1e-6) disc2(a,b,c); else disc3(a,b,c); return 0; } 3. #include #include void f(int a) { int i,n=(int)sqrt(a),t; for(i=2,t=1;i<=n;i++) { if(a%i==0) { t=0; printf("这是一个合数.\n");break; } } if(t) printf("这是一个素数.\n"); } int main() { int a; printf("请输入一个正整数a:"); scanf("%d",&a); f(a); return 0; } 4. #include void f(int a[3][3]) { int i,j,t; for(i=0;i<=2;i++) for(j=0;j { t=a[i][j]; a[i][j]=a[j][i]; a[j][i]=t; } } void main() { int i,j,a[3][3]={1,2,3,4,5,6,7,8,9}; for(i=0;i<=2;i++) { for(j=0;j<=2;j++) printf("%5d",a[i][j]); printf("\n"); } printf("\n"); f(a); for(i=0;i<=2;i++) { for(j=0;j<=2;j++) printf("%5d",a[i][j]); printf("\n"); } } 5. #include #include void f(char a[]) { int i,t; char b; t=strlen(a); for(i=0;i<=t/2;i++) { b=a[i]; a[i]=a[t-i-1]; a[t-i-1]=b; } } void main() { char ch[80]; gets(ch); f(ch); puts(ch); } 6. #include void f(char a[],char b[]) { int i,j; for(i=0;a[i]!='\0';i++); for(j=0;b[j]!='\0';i++,j++) a[i]=b[j]; } void main() { char ch1[80]="How do you do!",ch2[]="Fine,thank you,and you?"; f(ch1,ch2); puts(ch1); } 7. #include void f(char a[80],char b[40]) { int i,j; for(i=0,j=0;a[i]!='\0';i++) if(a[i]=='A'||a[i]=='E'||a[i]=='I'||a[i]=='O'||a[i]=='U'||a[i]=='a'||a[i]=='e'||a[i]=='i'||a[i]=='o' ||a[i]=='u') { b[j]=a[i]; j++; } b[j]='\0'; } int main() { char ch1[80]="How are you?Fine,thank you,and you?",ch2[40]; f(ch1,ch2); puts(ch2); return 0; } 8. #include void f(int n,int ch[]) { ch[0]=n/1000; ch[1]=(n-ch[0]*1000)/100; ch[2]=(n-ch[0]*1000-ch[1]*100)/10; ch[3]=n%10; } void main() { int n,i,ch[4]; printf("输入一个四位整数:\n"); scanf("%d",&n); f(n,ch); for(i=0;i<=3;i++) printf("%c ",ch[i]+48); } 9. #include int upp,low,num,space,other; void f(char c[]) { int i; for(upp=0,low=0,num=0,space=0,other=0,i=0;c[i]!='\0';i++) { if(c[i]>='A'&&c[i]<='Z') upp++; else if(c[i]>='a'&&c[i]<='z') low++; else if(c[i]>='0'&&c[i]<='9') num++; else if(c[i]==' ') space++; else other++; } } void main() { char ch[80]; printf("输入一句英文,限80字符内:\n"); gets(ch); f(ch); printf("大写字母%d个,小写字母%d个,数字%d个,空格%d个,其他%d个\n",upp,low,num,space,other); } 10. #include void f(char a[100],char b[40][30]) { int i,m,n,k,g; for(i=m=n=k=g=0;a[i]!='\0';i++) { if (a[i]>='a'&&a[i]<='z'||a[i]>='A'&&a[i]<='Z') { b[m][n]=a[i];//m单词位置n单词长度 n++; } else {