C语言基础常见计算题

源代码+截图以及运行：（有问题随时滴滴，一起学习呀）

  四则运算

#include 

int main (void)
{
	double A,B;
	char op;
	
	printf ("Type in an expression:");
	scanf ("%lf%c%lf", &A, &op, &B);
	if(op=='-')
	   printf("=% .2fn", A-B);
	else if(op=='+')
	   printf("=% .2fn", A+B);
	else if(op=='*')
	   printf("=% .2fn", A*B);
	else if(op=='/')
	  if (B!=0)
	   printf("=% .2fn", A/B);
	else
   	   printf("Divisor can not be 0!/n");
	else
	   printf("Unknown operator!/n");
	   
	return 0;
}

  计算分段函数

# include 
int main (void)
{
	double x,y;  
	
	printf("Enter x (x>=0): n" ); 
	scanf ("% lf ", &x);  
	
	if (x<=15) {
		y=4*x/3;
	} 
	else {
		y=2.5*x-10.5;
	}
	printf ("y=f (%f) =% .2fn",x,y);
	
	return 0;
 } 

调用幂函数pow()生成乘方表

#include 
#include 
int main (void)
{
	int i,n;
	double power;
	    
	    printf ("Enter n:");
	scanf ("%d", &n);
	for (i=0;i<=n;i++){
		power=pow (2,i);
		printf ("pow (2,%d) =% .0fn",i,power);
	}
	return 0;
 } 

    计算1-1/3+1/5-1/7+……

#include 
int main (void)
{
	int denominator, flag, i,n;
	double item, sum;
	
	printf ("Enter n:");
	scanf ("%d", &n);
	flag=1;
	denominator =1;
	sum=0;
	for (i=1; i<=n; i++){
		item=flag*1.0/denominator;
		sum=sum+item;
		flag=-flag;
		denominator=denominator+2;
	}
	printf ("sum=%fn",sum);
	
	return 0;
 } 

计算1+2+3+……+n

#include 
int main (void)
{
	int i,n,sum;
	printf ("Enter n:");
	scanf ("%d", &n);
	sum=0;
	for (i=1; i<=n; i++) {
		sum=sum+i;
	}
	printf ("Sum of numbers from 1 to %d is %dn",n,sum);
	
	return 0;
}

计算圆柱体积

#include 
double cylinder (double r,double h);
int main (void)
{
	double height,radius, volume;
	printf ("Enter radius and height:");
	scanf ("%lf%lf", &radius, &height);
	volume=cylinder (radius ,height);
	printf ("Volume=% .3fn",volume);
	
	return 0;
}

double cylinder (double r,double h)
{
	double result;
	
	result=3.14*r*r*h;
	
	return result;
}

  统计字符

#include 
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,dight=%d,other=%dn",letter,digit,other);
	
	return 0;
}

                                                                   计算存款的本息

# include 
# include  
int main (void)
{
	int money,year;
	double rate,sum;
	
	printf ("Enter money:");
	scanf ("%d",&money);
	printf ("Enter year:");
	scanf ("%d", &year);
	printf ("Enter rate:");
	scanf ("%lf", &rate);
	sum=money*pow (1+rate,year);
	printf ("sum=% .2fn", sum);
	
	 
	
	return 0;
 } 

#include
#include
int main(){
 
 
 
 
 float rate,year,money,sum;
scanf("%f %f %f",&rate,&year,&money);
 
 
 
 sum=pow(1+rate,year)*money;
 
 
 //printf("%d",pow(rate,year));
 printf("%.2f",sum);  // 注意 pow(2,2)  数据类型：float ，所以 %f ,就是 小数 
 
 
 
 
 return 0;
}

    计算平均分不及格人数

#include 
int main(void)
{
 int count ,num;
 double grade,total;
 
 num=0;
 total =0;
 count =0;
 printf ("Enter grades:");
 scanf ("%lf", &grade);
 
 while (grade>=0){
  total=total+grade;
  num++;
  if (grade<60)
     count++;
  scanf ("%f", &grade);
 }
 if (num!=0){
  printf("Grade average is % .2fn",total/num);
  printf("Number of failures is %dn",count);
 }
 else
     printf("Grade average is 0n");
     
     return 0;
 
}

#include 
int main(void)
{
 int count ,num;
 double grade,total;
 
 num=0;
 total =0;
 count =0;
 printf ("Enter grades:");
 scanf ("%lf", &grade);
 
 while (grade>=0){
  total=total+grade;
  num++;
  if (grade<60)
     count++;
  scanf ("%lf", &grade);
 }
 if (num!=0){
  printf("Grade average is % .2fn",total/num);
  printf("Number of failures is %dn",count);
 }
 else
     printf("Grade average is 0n");
     
     return 0;
 
}     

                                                          简单猜数游戏

#include 
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;
 } 

总结：

char 数据类型  op字符型变量

%d 整数  %c 单个字符 %lf 浮点型

for循环指定了循环次数

while循环知道循环结束条件

break强制循环结束除了中止循环外还用于switch语句

continue只是跳过后面语句继续循环

定义函数类型要明确是什么型

普通C语言教材三百多页，上面计算就有一百多页，弄懂上面计算就算C语言入门了已经懂了近四分之一，你以为就这？？？难的还在后面呢，最近我得再加把劲啊考试要来了