第二章：
程序清单
2.1
/* first.c */
#include <stdio.h>
int main(void) // a simple program
{
int num; // define a variable called num
num = 1; // aasign a value to num
printf("I am a simple "); // use the printf() function
printf("computer.\n");
printf("My favorite number is %d because it is first.\n", num);
return 0;
}2.2
// fathom_ft.c -- convert 2 fathoms into feet
#include <stdio.h>
int main(void)
{
int fathoms, feet;
fathoms = 2;
feet = fathoms * 6;
printf("There are %d feet in %d fathoms!\n", feet, fathoms);
printf("Yes, I said %d feet!\n", 6 * fathoms);
return 0;
}
2.3
// two_func.c -- a program using two functions in a file
#include <stdio.h>
void bulter(void); /* ANSI/ISO C function prototyping */
int main (void)
{
printf("I will summon the bulter function.\n");
bulter();
printf("Yes. Bring me some tea and writeable"
" DVDs.\n");
return 0;
}
void bulter(void) // start a function of definition
{
printf("You rang, sir?\n");
}
2.4
/* nogood.c -- a program with errors */
#include <stdio.h>
int main(void)
(
int n, int n2, int n3;
/* this program have several errors */
n = 5;
n2 = n * n;
n3 = n2 * n2;
printf("n = %d, n squared = %d, n cubed = %d\n", n, n2, n3)
return 0;
) 2.5
/* stillbad.c -- a program with its syntax errors fixed */
#include <stdio.h>
int main(void)
{
int n, n2, n3;
/* this program with a semantic error */
n = 5;
n2 = n * n;
n3 = n2 * n2;
printf ("n = %d, n squared = %d, n cubed = %d\n",
n, n2, n3);
return 0;
}
2.6
/* good.c -- a program with its syntax and semantic errors fixed */
#include <stdio.h>
int main(void)
{
int n, n2, n3;
/* this program with a semantic error */
n = 5;
n2 = n * n;
n3 = n2 * n;
printf ("n = %d, n squared = %d, n cubed = %d\n",
n, n2, n3);
return 0;
}
复习题答案:
1. C语言的基本模块是什么？
answer: function
2. 什么是语法错误？写出一个英语例子和C语言例子.
answer:
A syntax error is a violation of the rules governing how sentences or programs are put together.
Here’s an example in English: “Me speak English good.”
Here’s an example in C: printf"Where are the parentheses?"
3. 什么是语义错误， 写出一个英语例子和C语言例子。
answer:
A semantic error is one of meaning.
Here’s an example in English: “This sentence is excellent Czech.”
Here’s a C example: thrice_n = 3 + n;
4.
// after correct aq2_4.c
#include <stdio.h>
int main(void) // this program prints the number of weeks in a year
{
int s;
s = 56;
printf ("There are %d weeks in a year.\n", s);
return 0;
}
~ 5.
#include <stdio.h>
int main(void)
{
// a
printf("Baa Baa Black Sheep.");
printf("Have you any wool?\n");
// b
printf("Begone!\nO creature of lard!\n");
// c
printf("What?\nNo/nfish?\n");
// d
int num;
num = 2;
printf("%d + %d = %d", num, num, num + num);
return 0;
}
6. Which of the following are C keywords? main, int, function, char, =
answer: int and char
(main is a function name, function is a technical term for describing C,
and = is an operator).
7
#include <stdio.h>
int main(void)
{
int words = 3020, lines = 350;
printf("There were %d words and %d lines.\n", words, lines);
return 0;
}
8
include <stdio.h>
int main(void)
{
int a, b;
a = 5;
b = 2; /* line 7 */
printf("a = %d, b = %d\n", a, b);
b = a; /* line 8 */
printf("a = %d, b = %d\n", a, b);
a = b; /* line 9 */
printf("a = %d, b = %d\n", a, b);
printf("%d %d\n", b, a);
return 0;
}
9.
#include <stdio.h>
int main(void)
{
int x, y;
x = 10;
y = 5; /* line 7 */
printf("x=%-3d y=%d\n", x, y);
y = x + y; /* line 8 */
printf("x=%-3d y=%d\n", x, y);
x = x*y; /* line 9 */
printf("x=%-3d y=%d\n", x, y);
printf("%d %d\n", x, y);
return 0;
}
编程练习：
1.
#include <stdio.h>
int main(void)
{
printf("Luyu Pan\n");
printf("Luyu \nPan\n");
printf("Luyu ");
printf("Pan\n");
return 0;
}
2.
* 2. Write a program to print your name and address. */
#include <stdio.h>
#define NAME "Luyu Pan"
#define ADDRESS "FuShun"
int main(void)
{
printf("My name is %s, My address is %s.\n", NAME, ADDRESS);
return 0;
}
3.
#include <stdio.h>
#define YEAR 365
int main(void)
{
int age = 20;
int days = age * YEAR;
printf("My age is %d, equals %d days.\n", age, days);
return 0;
}
4.
#include <stdio.h>
void jolly(void); // ASNI prototype
void deny(void);
int main(void)
{
for(int i = 0; i < 3; i++)
jolly(); // call function jolly()
deny();
return 0;
}
void jolly(void) // function definition
{
puts("For he's a jolly good fellow!");
}
void deny(void)
{
puts("Which nobody can deny!");
}
5.
#include <stdio.h>
void br(void);
void ic(void);
int main(void)
{
br();
putchar(',');
putchar(' ');
ic();
putchar('\n');
ic();
putchar(',');
putchar('\n');
br();
putchar('\n');
return 0;
}
void br(void)
{
printf("Brazil, Russia");
}
void ic(void)
{
printf("India, China");
} 6.
#include <stdio.h>
int main(void)
{
int toes = 10;
printf("toes = %d, twice toes = %d, toes squared = %d\n",
toes, toes * 2, toes * toes);
return 0;
}7.
#include <stdio.h>
#define TIMES 3
void smile(void);
int main(void)
{
for (int i = 0; i < TIMES; i++)
{
for (int j = TIMES; j > i; j--)
smile();
putchar('\n');
}
return 0;
}
void smile(void)
{
printf("Smile!");
} 8.
#include <stdio.h>
void one_three(void);
void two(void);
int main(void)
{
puts("Starting now:");
one_three();
puts("done!");
return 0;
}
void one_three(void)
{
puts("one");
two(); // one function call another function
puts("three");
}
void two(void)
{
puts("two");
}