第三章
3-1
#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; }
3-2
#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; }
3-3
#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; }
3-4
#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; }
3-5
#include<stdio.h> int main(void) { double value1,value2; char op; printf("Type in 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=='/') printf("=%.2f\n",value1/value2); else printf("Unknown operator\n"); return 0; }
3-7
#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; }
3-8
#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; }
3-9
#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; } return 0; }
3-10
#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; }
3-11
#include<stdio.h> int main(void) { double value1,value2; char op; printf("Type in 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; }