homework.txt

c primer 部分习题答案

2-1
 

#include <stdio.h>
int main(void)
{
    printf("谢锦明\n");
    printf("谢\n");
    printf("锦明\n");
    printf("谢锦明\n");
 
    return 0;
}

2-2


#include <stdio.h>
int main(void)
{
	printf("泉州晋江\n");
	printf("谢锦明\n");
	return 0;
}
 
2-3
 

#include <stdio.h>
int main(void)
{
    int a，days;
    printf("Enter an age:\n");
    scanf("%d",&a);
    days = 365 * a;
    printf("the age is %d days.\n", a, days);
 
    return 0;
}
 
 
2-4
 

#include <stdio.h>
void fellow(void);
void deny(void);
int main(void)
{
    fellow();
    fellow();
    fellow();
    deny();
 
    return 0;
}

void fellow(void)
{
    printf("For he's a fellow good fellow!\n");
}

void deny(void)
{
    printf("Which nobody can deny!\n");
}
 
2-5
 

#include <stdio.h>
int main(void)
{
    int toes = 10;
        
    printf("toes = %d\n", toes);
    printf("Twice toes = %d\n", 2 * toes);
    printf("toes squared = %d\n", toes * toes);
 
    return 0;
}
 

 
2-7


#include <stdio.h>
void one_three(void);
void two(void);
int main(void)
{
    printf("starting now:\n");
    one_three();
    printf("done!\n");
    return 0;
}
 
void one_three(void)
{
    printf("one\n");
    two();
    printf("three\n");
}
 
void two(void)
{
    printf("two\n");
}
Chapter 3
 
PE 3-2
 

#include <stdio.h>
int main(void)
{
    int a;
    
    printf("Enter an ASCII code: ");
    scanf("%d", &a);
    printf("%d is the ASCII code for %c.\n", a, a);
 
    return 0;
}

3-3


#include <stdio.h>
int main(void)
{
	char x=34;
	printf("\a");
	printf("Startled by sudden sound,Sally shouted,%cBy the Great Pumpkin,what was that!%C\n",x,x);
	return 0;
}

 
3-4
 

#include <stdio.h>
int main(void)
{
    float n;

    printf("Enter a floating-point value: ");
    scanf("%f", &n);
    printf("The input is %f or %e\n",n,n);

    return 0;
}


3-5


#include <stdio.h>
int main(void)
{
	long float age;
	printf("Enter an age:\n");
	scanf("%lf",&age);
	printf("%lf second\n",age*31560000);
	return 0;
}

 
3-6
 

#include <stdio.h>
int main(void)
{
    float a,b,q,m;
    a = 3.0e-23;
    b = 950
    
    printf("Enter the number of quarts of water: ");
    scanf("%f", &q);
    molecules = q * b / a;
    printf("%f quarts of water contain %e molecules.\n", q, m);
 
    return 0;
}
 

3-7


#include <stdio.h>
int main(void)
{
	float h;

	printf("Enter a height(in inch)\n");
	scanf("%f",&h);
	printf("%f cm\n",h*2.54);

	return 0;
}


4-1
 
/* Programming Exercise 4-1  */
#include <stdio.h>
 
int main(void)
{
    char fir[40],las[40];
    
    printf("Enter your first name: ");
    scanf("%s", &fir);
    printf("Enter your last name: ");
    scanf("%s", &las);
    printf("%s, %s\n", fir, las);
 
    return 0;
}


4-3


#include <stdio.h>
int main(void)
{
	float num;

        printf("Enter an floating-point number:");
	scanf("%f",&num);
	printf("The input is %f or %e\n",num,num);

	return 0;
}


 
PE 4-4
 

#include <stdio.h>
int main(void)
{
    float height;
    char name[40];
    
    printf("Enter your height in inches: ");
    scanf("%f", &height);
    printf("Enter your name: ");
    scanf("%s", name);
    printf("%s, you are %.3f feet tall\n", name, height / 12.0);
    
    return 0;
}


 
PE 4-6
 

#include <stdio.h>
#include <float.h>
 
int main(void)
{
    float a = 1.0 / 3.0;
    double b = 1.0 / 3.0;
    
    printf(" float values: ");
    printf("%.4f %.12f %.16f\n", a, b, b);
    printf("double values: ");
    printf("%.4f %.12f %.16f\n", b, b, b);
    printf("FLT_DIG: %d\n", FLT_DIG);
    printf("DBL_DIG: %d\n", DBL_DIG);
    return 0;
}
 

 
5-1
 

#include <stdio.h>
#define X 60
int main(void)
{
	int a,b,c;
	printf("Enter the minutes\n");
	while((scanf("%d",&a)==1)&&(a>0))
	{
		b=a/X;
		c=a%X;
		printf("%d hour %d minute\n",b,c);
	}
	printf("Enter error\n");
	return 0;
}



5-2


#include <stdio.h>
int main(void)
{
	int a,b;
	printf("please Enter some numbers\n");
	scanf("%d",&a);
	b=a;
	for(; a<=b+10;a++)
		printf("%d ",a);
	printf("\n");
	return 0;
}
	
 
5-3
 

#include <stdio.h>
#define daysweek 7
int main(void)
{
    const int daysweek = 7;
    int days, weeks, d;
    
    printf("Enter the number of days: ");
    scanf("%d", &days);
    weeks = days / daysweek;
    d = days % daysweek;
        
    printf("%d days are %d weeks and %d days.\n", days, weeks, d);
    
    return 0;
}
 


5-5
 

#include <stdio.h>
int main(void)  
{
  int count, sum;            
  int n;
  
  printf("Enter the upper limit: ");
  scanf("%d", &n);
  count = 0;                  
  sum = 0;                  
  while (count++ < n)
     sum = sum + count; 
  printf("sum = %d\n", sum);
  return 0;
}
 


5-7


#include <stdio.h>
void showCube(double x);
int main(void)
{
     double val;
     
     printf("Enter a floating-point value: ");
     scanf("%lf", &val);
     showCube(val);
     
    return 0;
}
 
void showCube(double x)
{
    printf("The cube of %e is %e.\n", x, x*x*x );
}
 

6-1
 


#include <stdio.h>
#define SIZE 26
int main( void )
{
    char lcase[SIZE];
    int i;
    
    for (i = 0; i < SIZE; i++)
        lcase[i] = 'a' + i;
    for (i = 0; i < SIZE; i++)
        printf("%c", lcase[i]);
    printf("\n");        
 
    return 0;
}
 

6-2


#include <stdio.h>
int main(void)
{
	int a,b;
	for(a=1;a<=5;a++)
	{
		for(b=1;b<=i;b++)
			printf("$");
		printf("\n");
	}
	return 0;
}



6-3
 

 #include <stdio.h>
int main(void)
{
	char a;
	int b;
	for(b=1;b<=6;b++)
	{
		for(a='F';a>'F'-b;b--)
			printf("%c",a);
		printf("\n");
	}
	return 0;
}
 

6-4


#include <stdio.h>
int main(void)
{
	char ch;
	int a;
	while((ch=getchar())!='#')
	{
		if(ch=='.')
		{
			printf("!");
			a++;
			continue;
		}
		if(ch=='!')