《C语言程序设计》第三章例题源代码

[例3-1]
#include<stdio.h>
int main(void)
{
int digit,i,letter,other;
char ch;
digit=letter=other=0;
printf("Enter 10 characters:");
for(i=1;i<=10;i )
{
ch=getchar();
if((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z'))
letter ;
else if(ch>='0'&&ch<='9')
digit ;
else
other ;
}
printf("letter=%d,digit=%d,other=%d\n",letter,digit,other);
return 0;
}
[例3-3]
#include<stdio.h>
int main(void)
{
double x,y;
printf("Enter x:");
scanf("%lf",&x);
if(x<0)
{
y=0;
}
else if(x<=15)
{
y=4*x/3;
}
else
{
y=2.5*x-10.5;
}
printf("f(%.2f)=%.2f\n",x,y);
return 0;
}
[例3-4]
#include<stdio.h>
int main(void)
{
int choice,i;
double price;
for(i=1;i<=5;i )
{
printf("[1] Select crisps\n");
printf("[2] Select popcorn\n");
printf("[3] Select chocolate\n");
printf("[4] Select cola\n");
printf("[0] exit\n");
printf("Enter choice:");
scanf("%d",&choice);
if(choice==0)
break;
switch(choice)
{
case 1:price=3.0;break;
case 2:price=2.5;break;
case 3:price=4.0;break;
case 4:price=3.5;break;
default:price=0.0;break;
}
printf("price=%0.1f\n",price);
}
printf("Thanks\n");
return 0;
}
[例3-5]
#include<stdio.h>
int main(void)
{
double value1,value2;
char operato;
printf("Type in an expression:");
scanf("%lf%c%lf",&value1,&operato,&value2);
switch(operato)
{
case' ':
printf("=%.2f\n",value1 value2);
break;
case'-':
printf("=%.2f\n",value1-value2);
break;
case'*':
printf("=%.2f\n",value1*value2);
break;
case'/':
printf("=%.2f\n",value1/value2);
break;
default:
printf("Unknown operator\n");
break;
}
return 0;
}
[例3-6]
#include<stdio.h>
int main(void)
{
int blank,digit,i,other;
char ch;
blank=digit=other=0;
printf("Enter 10 characters:");
for(i=1;i<=10;i )
{
ch=getchar();
switch(ch)
{
case' ':
case'\n':
blank ;
break;
case'0':case'1':case'2':case'3':case'4':
case'5':case'6':case'7':case'8':case'9':
digit ;
break;
default:
other ;
break;
}
}
printf("blank=%d,digit=%d,other=%d\n",blank,digit,other);
return 0;
}
[例3-7]
#include<stdio.h>
int main(void)
{
int number;
printf("Enter a number:");
scanf("%d",&number);
if(number%2==0)
{
printf("The number is even.\n");
}
else
{
printf("The number is odd.\n");
}
return 0;
}
【例3-8】
#include<stdio.h>
int main(void)
{
int number;
printf("Enter a number:");
scanf("%d",&number);
if(number<0)
{
number=-number;
}
printf("The absolute value is %d.\n",number);
return 0;
}
【例3-9】
#include<stdio.h>
int main(void)
{
int count,i,n;
double grade,total;
printf("Enter n:");
scanf("%d",&n);
total=0;
count=0;
for(i=1;i<=n;i )
{
printf("Enter grade #%d:",i);
scanf("%lf",&grade);
total=total grade;
if(grade<60)
{
count ;
}
}
printf("Grade average = %.2f\n",total/n);
printf("Number of failures = %d\n",count);
return 0;
}