例题第3章

#include<stdio.h>
int main(void)
{
int mynumber=38;
int yournumber;

printf("Input your number:");
scanf("%d",&yournumber);
if(yournumber==mynumber)
printf("Ok!you are right!\n");
else
if(yournumber>mynumber)
printf("Sorry!your number is bigger than my number!\n");
else
printf("Sorry!your number is smaller than my number!\n");

return 0;
}

#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;
}

#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;
}

#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;
}

#include<stdio.h>
int main(void)
{
double valuel,value2;
char op;
printf("Type in an expression:");
scanf("%lf%c%lf",&valuel,&op,&value2);

if(op=='+')
printf("=%.2f\n",valuel+value2);
else if(op=='-')
printf("=%.2f\n",valuel-value2);
else if(op=='*')
printf("=%,2f\n",valuel*value2);
else if(op=='/')
printf("=%.2f\n",valuel/value2);
else
printf("Unknown operator\n");

return 0;
}

#include<stdio.h>
int main(void)
{
int digit,letter,other;
char ch;
int i;
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;
}

#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;
}

#include<stdio.h>
int main(void)
{
double value1,value2;
char op;

printf("Type in an expression:");
scanf("%lf%c%lf",&value1,&op,&value2);
switch(op){
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;
}

#include<stdio.h>
int main(void)
{
int blank,digit,other;
char ch;
int i;
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;
}

#include<stdio.h>
int main(void)
{
double value1,value2;
char op;

printf("Type is an expression:");
scanf("%lf%c%lf",&value1,&op,&value2);
if(op=='+')
printf("=%.2f\n",value1+value2);
else if(op=='-')
printf("=%.2f\n",value1-value2);
else if (op=='*')
printf("=%.2f\n",value1*value2);
else if(op == '/')
if(value2!=0)
printf("=%,2f\n",value1/value2);
else
printf("Divisor can not be 0!\n");
else
printf("Unknown operator!\n");

return 0;
}