= 实验课基本要求 =
 * 实验课前对实验内容做好预习
 * 有效利用实验课时间，不做与实验无关的活动
 * 独立完成实验内容
 * 按时提交实验报告，发送到 czk19790827@gmail.com
 * 实验报告模板：<<AttachList>>

= 实验运行环境简介 =
[[C++集成开发环境]]

如果机房电脑速度太慢参看[[温大机房优化脚本]]

= 实验1-1 =

== 实验目的 ==
熟悉C语言开发环境，学会
 * 创建工程
 * 编辑代码
 * 编译连接，生成可执行程序
 * 调试代码

== 实验内容 ==
编译运行以下程序，观察程序运行的结果
完成课后作业1-1

{{{#!cplusplus
#include <stdio.h>
main() 
{
        printf("hello, world\n");
}
}}}

{{{#!cplusplus
#include <stdio.h>
/* print Fahrenheit-Celsius table for fahr = 0, 20, ..., 300 */
main ()
{
    int fahr,  celsius;
    int lower, upper, step;
    lower = 0;
    upper = 300;
    step = 20;
    fahr = lower;
    while ( fahr <= upper) {
        celsius = 5 * (fahr - 32) / 9;
        printf( "%d\t%d\n", fahr, celsius);
        fahr = fahr + step;
    } 
}
}}}
{{{#!cplusplus
#include <stdio.h>
/* print Fahrenheit-Celsius table*/
main()
{
    int fahr;

    for (fahr = 0; fahr <= 300; fahr = fahr + 20)
        printf("%3d %6.1f\n", fahr, (5.0/9.0)*(fahr-32));
}
}}}

{{{1-1 Run the "hello, world" program on your system. Experiment with leaving out parts of the program, to see what error messages you get.
}}}

= 实验1-2 =
== 实验目的 ==
 * 掌握C语言变量、循环的基本概念
 * 掌握基本的算术运算 

== 实验内容 ==
完成课后作业1-4，1-5 
 * Write a program to print the corresponding Celsius to Fahrenheit table.
 * Modify the temperature conversion program to print the table in reverse order, that is, from 300 degrees to 0.

= 实验1-3 =
== 实验名称 ==
函数的编写
== 实验目的 ==
 * 掌握C语言函数的基本概念 
 * 掌握C语言函数的定义和调用方法 
 * 理解C语言字符串和字符数组的使用方法 

== 实验内容 ==

完成课后作业1-17: Write a program to print all lines that are longer than 80 characters. 

= 实验1-4 =
== 实验目的 ==

掌握位运算符的基本用法

== 实验内容 ==

完成课后习题2-8: Write a function rightrot(x,n) that returns the value of the integer x rotated to the right by n positions. 

= 实验1-5 =
== 实验目的 ==

 * 掌握关系表达式和IF语句
 * 掌握循环的使用方法
 * 巩固C语言数组、字符串的使用方法

== 实验内容 ==

练习1-19

Write a function reverse(s) that reverses the character string s. Use it to write a program that reverses its input a line at a time.

= 实验1-6 =
== 实验目的 ==

== 实验内容 ==
Write a version of itoa that accepts three arguments instead of two. The third argument is a minimum field width; the converted number must be padded with banks on the left if necessary to make it wide enough.

= 实验1-7 =
== 实验目的 ==
 * 掌握全局变量使用方法 
 * 掌握多文件的组织方法 
== 实验内容 ==
Exercise 4-3. Given the basic framework, it's straightforward to extend the calculator. Add the modulus (%) operator.

= 实验1-8 =
== 实验目的 ==
掌握递归函数的编写方法

== 实验内容 ==
Write a recursive version of the function reverse(s), which reverses the string s in place.

= 实验1-9 =

== 实验内容 ==
书中给定了栈的数据结构和两个操作函数（push,pop），请在此基础上添加
{{{top函数：取栈顶元素
empty函数：判断栈是否为空，栈非空返回0，栈为空返回非零
size函数：返回栈中元素的个数
clear函数：清空栈
print函数：打印栈中每一个元素}}}
添加这些函数后，使以下main函数能够正确运行：
{{{#!cplusplus
main()
{
    push(1);
    push(2);
    push(3);
    printf("size:%d\n", size() );
    printf("top:%f\n", top() );
    printf("stack is%s empty\n", (empty() ?"":" not" ));
    printf("content: ");
    print();
    printf("\n");
    clear();
    printf("size:%d\n", size());
    printf("stack is%s empty\n", (empty() ?"":" not" ));
}
}}}
正确的输出应该为：
{{{size:3
top:3
stack is not empty
content: 1 2 3
size:0
stack is empty
}}}

= 实验1-10 =

== 实验内容 ==

写一个程序，输入一组整数，计算它们的平均值。 
例如：输入 
{{{100 
80 
60 
40}}}
输出 
{{{70 
}}}
提示：调用getint实现 

= 实验1-11 =
== 实验名称 ==
函数的编写
== 实验目的 ==
 * 掌握简单函数的声明和定义
 * 掌握函数的调用方法
== 实验内容 ==

用指针的方式实现课后练习4-1: Write the function strrindex(s,t), which returns the position of the rightmost occurrence of t in s, or -1 if there is none.

= 实验2-1 =
== 实验目的 ==
== 实验内容 ==
写一个函数strinsert(s, n, t)在字符串s的第n个字符后面插入字符串t。比如：
{{{#!cplusplus
char s[100] = "write everywhere";
char t[] = "once, run ";
strinsert(s, 6, t);
printf("%s", s); 
}}}
输出：
{{{write once, run everywhere
}}}
== 参考程序 ==
{{{#!cplusplus
void strinsert(char *s, int i, char *t) {
   int tlen = strlen(t);
   int slen = strlen(s);
   int j;

   for(j = slen; j >= i; j--)
      s[j+tlen] = s[j];
   for(j = 0; j < tlen; j++)
      s[j+i] = t[j];
}
}}}

= 实验2-2 =
== 实验目的 ==
== 实验内容 ==
写两个函数
 * strcrop(s, i, j) 取字符串s中第i个到第j个字符
 * strdel(s, i, j) 将字符串s中第i个到第j个字符删除
for example:
{{{#!cplusplus
char s[20]="hello world";
char t[20]="hello world";
strcrop(s, 1, 8);
strdel(t, 1, 8);
printf("%s\n%s\n", s, t); 
}}}
output:
{{{
ello wor
hld 
}}}

== 参考程序 ==
{{{#!cplusplus
void strcrop(char *s, int i, int j) {
    int k;
    for(k = i; k <=j; k++)
        s[k-i] = s[k];
    s[k] = '\0';
}
void strdel(char *s, int i, int j) {
    j++;
    while(s[j] != '\0')
        s[i++] = s[j++] 
    s[i] = '\0';
}
}}}

= 实验2-3 =
== 实验目的 ==
熟悉指针数组的使用
== 实验内容 ==
写一个函数weekday(y,m,d)，求取y年m月d日是星期几，返回星期几的名字。例如：
{{{#!cplusplus
printf("%s", weekday(2006,3,6));
}}}输出
{{{Monday
}}}

= 实验2-4 =
== 实验目的 ==
掌握多维数组的使用
== 实验内容 ==
写一个函数{{{void inverse(int matrix[N][N])}}}，将矩阵matrix转置。比如
{{{#!cplusplus
#define N 3
int m[N][N] = {
  {1, 2, 3},
  {4, 5, 6},
  {7, 8, 9}
};
inverse(m);
}}}得到结果：
{{{
m =
1 4 7
2 5 8
3 6 9
}}}
== 参考程序 ==
{{{#!cplusplus
void inverse(int matrix[N][N]) {
    int i, j;
    for(i = 0; i < N; i++) { 
        for(j = 0; j < i; j++) {
            int temp = matrix[i][j];
            matrix[i][j] = matrix[j][i];
            matrix[j][i] = temp;
        }
    }
}
}}}

= 实验2-5 =
== 实验目的 ==
掌握命令行参数的获取和使用

== 实验内容 ==

修改1-20题的程序，使其可以使用命令行参数来指定tab终止位的宽度。比如
{{{
detab -10
}}}
指定tab终止位为每10个字符一个。（这里，detab为程序的名字，-10为参数。）

= 实验2-6 =
== 实验目的 ==
练习函数指针的使用方法

== 实验内容 ==
写一个函数strfilter，删除字符串中的满足一定条件的字符
{{{#!cplusplus
void strfilter(char s[], int (*fun)(int) );
int filter (int c){ 
   return !islower(c) && !isuper(c); 
}
main() {
   char str1[]="Hello, world";
   char str2[]="Hello, world";
   char str3[]="Hello, world";
   strfilter(str1, isupper);/*ello, world*/
   strfilter(str2, islower);/*H, */
   strfilter(str3, filter);/*Helloworld*/
   printf("%s\n%s\n%s\n", str1, str2, str3);
}
}}}
== 参考程序 ==
{{{#!cplusplus
void strfilter(char *s, int (*fun)(int c)) {
    char *t = s;
    while(*s !='\0') {
        if(!(*fun)(c)) {
            *t = *s;
            t++;
        }
        s++;
    }
}
}}}

= 实验2-7 =

== 实验目的 ==
练习结构体的简单使用

== 实验内容 ==
 * write a function to calculate distance between two points.
 * write a function to calculate the area of a rect.

== 参考程序 ==
{{{#!cplusplus
struct point {
    int x, y;
};
struct rect {
    struct point p1, p2;
};
double distance(struct point p1, struct point p2) {
    return sqrt((p1.x - p2.x)*(p1.x - p2.x) + (p1.y - p2.y)*(p1.y - p2.y));
}
int area(struct rect r) {
    return (r.p1.x - r.p2.x) * (r.p1.y - r.p2.y);
}
}}}

= 实验2-8 =
== 实验目的 ==

掌握结构体的进一步使用

== 实验内容 ==

Write a program that prints the distinct words in its input sorted into increasing order of frequency of occurrence. The words with frequency lower than 3 are omitted. Make 3 a parameter that can be set from the command line.

== 参考程序 ==

{{{#!cplusplus
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdlib.h>

#define MAXWORD 100
#define MAX 1000

struct key {
   char word[MAXWORD];
   int count;
} keytab[MAX];
int size = 0;

int getword(char *, int);
int binsearch(char *, struct key *, int);
int comp(struct key w1, struct key w2);
void qsort2(struct key v[], int left, int right,
          int (*comp)(struct key, struct key));
void swap(struct key v[], int i, int j);

/* count C keywords */
main(int argc, char *argv[])
{
    int n;
    char word[MAXWORD];
    
    int least_count = 3;
   
    /*read parameter from command line*/
    if(argc>1) {
        least_count = atoi(argv[1]);
    }

    /*read and count words*/
    while (getword(word, MAXWORD) != EOF)
        if (isalpha(word[0]))
            if ((n = binsearch(word, keytab, size)) >= 0)
                keytab[n].count++;
            else {
                strcpy(keytab[size].word, word);
                keytab[size].count = 1;
                size++;
            }
    /*sort*/
    qsort2(keytab, 0, size-1, &comp);            

    /*output*/
    for (n = 0; n < size; n++)
       if (keytab[n].count >=least_count )
           printf("%4d %s\n", keytab[n].count, keytab[n].word);
    system("pause");
    return 0;
}

/* qsort:  sort v[left]...v[right] into increasing order */
void qsort2(struct key v[], int left, int right,
          int (*comp)(struct key, struct key))
{
   int i, last;

   if (left >= right)    /* do  nothing if array contains */
       return;           /* fewer than two elements */
   swap(v, left, (left + right)/2);
   last = left;
   for (i = left+1; i <= right;  i++)
       if ((*comp)(v[i], v[left]) < 0)
           swap(v, ++last, i);
   swap(v, left, last);
   qsort2(v, left, last-1, comp);
   qsort2(v, last+1, right, comp);
}

int comp(struct key w1, struct key w2) {
    return w1.count - w2.count;
}

void swap(struct key v[], int i, int j) {
    struct key temp;
    temp = v[i];
    v[i] = v[j];
    v[j] = temp;
}

/* binsearch:  find word in tab[0]...tab[n-1] */
int binsearch(char *word, struct key tab[], int n)
{
    int i;
    for(i = 0; i < n; i++)
        if( strcmp( word,  tab[i].word)==0)
            return i;
    return -1;
}

#define BUFSIZE 100

char buf[BUFSIZE]; /* buffer for ungetch */ 
int bufp = 0; /* next free position in buf */
int getch(void) /* get a (possibly pushed-back) character */ 
{
      return (bufp > 0) ? buf[--bufp] : getchar(); 
}

void ungetch(int c) /* push character back on input */ {
      if (bufp >= BUFSIZE)
            printf("ungetch: too many characters\n"); 
      else
            buf[bufp++] = c; 
}

/* getword:  get next word or character from input */
int getword(char *word, int lim)
{
   int c;
   char *w = word;

   while (isspace(c = getch()))
       ;
   if (c != EOF)
       *w++ = c;
   if (!isalpha(c)) {
       *w = '\0';
       return c;
   }
   for ( ; --lim > 0; w++)
       if (!isalnum(*w = getch())) {
           ungetch(*w);
           break;
       }
   *w = '\0';
   return word[0];
}

}}}


= 实验2-9 =

== 实验目的 ==

掌握结构体数组的使用

== 实验内容 ==

按要求完成ZJU Online Judge第2104题：http://acm.zju.edu.cn/show_problem.php?pid=2104


== 参考程序 ==
{{{#!cplusplus
#include <stdio.h>

struct balloon {
    char color[16];
    int count;
};

int main() {
    while(1) {
        int n, i;
        int found;
        struct balloon balloons[1000];
        int size = 0;
        char color[16];
        int max, max_i;
         
        getint(&n);
        if(n==0) break;
        for(i = 0; i < n; i++) {
            getword(color, 16);
            if((found = search(color, balloons, size)) >=0)
                balloons[found].count++;
            else {
                strcpy(balloons[size].color, color);
                balloons[size].count = 1;
                size++;
            }            
        }
        
        max_i = -1;
        max = 0;
        for(i = 0; i < size; i++) {
            if(balloons[i].count > max) {
                max = balloons[i].count;
                max_i = i;
            }
        }
        printf("%s\n", balloons[max_i].color);       
    }   
    return 0;
}

/* search:  find word in tab[0]...tab[n-1] */
int search(char *word, struct balloon tab[], int n)
{
    int i;
    for(i = 0; i < n; i++)
        if(strcmp(tab[i].color, word)==0)
            return i;
    return -1;
}

#define BUFSIZE 100

char buf[BUFSIZE]; /* buffer for ungetch */ 
int bufp = 0; /* next free position in buf */
int getch(void) /* get a (possibly pushed-back) character */ 
{
      return (bufp > 0) ? buf[--bufp] : getchar(); 
}

void ungetch(int c) /* push character back on input */ {
      if (bufp >= BUFSIZE)
            printf("ungetch: too many characters\n"); 
      else
            buf[bufp++] = c; 
}

/* getword:  get next word or character from input */
int getword(char *word, int lim)
{
   int c;
   char *w = word;

   while (isspace(c = getch()))
       ;
   if (c != EOF)
       *w++ = c;
   for ( ; --lim > 0; w++)
       if (isspace(*w = getch())) {
           ungetch(*w);
           break;
       }
   *w = '\0';
   return word[0];
}


int getint(int *pn)
{
   int c, sign;

   while (isspace(c = getch()))   /* skip white space */
       ;
   if (!isdigit(c) && c != EOF && c != '+' && c != '-') {
       ungetch(c);  /* it is not a number */
       return 0;
   }
   sign = (c == '-') ? -1 : 1;
   if (c == '+' || c == '-')
       c = getch();
   for (*pn = 0; isdigit(c); c = getch())
       *pn = 10 * *pn + (c - '0');
   *pn *= sign;
   if (c != EOF)
       ungetch(c);
   return c;
}

}}}


= 实验2-10 =

== 实验目的 ==

掌握自引用结构体的使用

== 实验内容 ==

统计输入中不同单词的个数。使用链表实现。


== 参考程序 ==
{{{#!cplusplus
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAXWORD 1000
struct node {
    char *word;
    int count;
    struct node *next;
};
struct node*addlist(struct node *head, char *w);
char *strdup(char *s);
void listprint(struct node *p);

main() {
    struct node *head = NULL;
    char word[MAXWORD];
    while(getword(word, MAXWORD)!=EOF)
        if(isalpha(word[0]))
            head = addlist(head, word);
    listprint(head);
    system("pause");
}

void listprint(struct node *p) {
    while(p!=NULL) {
        printf("%4d %s\n", p->count, p->word);
        p = p->next;
    }
}

struct node*addlist(struct node *head, char *w){
    int cond;
    struct node *p = head, *pre = NULL;
    while(p!=NULL) {
        cond=strcmp(w,p->word);
        if(cond == 0) {
            p->count ++;
            return head;
        } else if(cond > 0) {
            pre = p; p = p->next;
        } else
            break;
    }
    p =(struct node*)malloc(sizeof(struct node));
    p->word = strdup(w);
    p->count = 1;
    if(pre == NULL) {
        p->next = head;
        head = p;   
    } else {
        p->next = pre->next;
        pre->next = p;
    }
    return head;
}

char *strdup(char *s) {
    char *p = (char *)malloc(strlen(s)+1);
    strcpy(p, s);
    return p;
}

#define BUFSIZE 100

char buf[BUFSIZE]; /* buffer for ungetch */ 
int bufp = 0; /* next free position in buf */
int getch(void) /* get a (possibly pushed-back) character */ 
{
    return (bufp > 0) ? buf[--bufp] : getchar(); 
}

void ungetch(int c) /* push character back on input */ {
    if (bufp >= BUFSIZE)
        printf("ungetch: too many characters\n"); 
    else
        buf[bufp++] = c; 
}

int getword(char *word, int lim)
{
    int c;
    char *w = word;

    while (isspace(c = getch()))
        ;
    if (c != EOF)
        *w++ = c;
    if (!isalpha(c)) {
        *w = '\0';
        return c;
    }
    for ( ; --lim > 0; w++)
        if (!isalnum(*w = getch())) {
            ungetch(*w);
            break;
        }
    *w = '\0';
    return word[0];
}

}}}

= 实验2-11 =

== 实验目的 ==

掌握C语言的输入输出

== 实验内容 ==

Exercise 7-1. Write a program that converts upper case to lower or lower case to upper, depending on the name it is invoked with, as found in argv[0]. 

== 参考程序 ==

{{{#!cplusplus
#include <stdio.h>
#include <ctype.h>
main(int argc, char * argv[]) {
    int c;
    int (*convert)(int);
    
    convert = (strstr(argv[0],"tolower")!=NULL) ? tolower : toupper;
    while((c=getchar())!=EOF)
        putchar(convert(c));
}
}}}

= 实验2-12 =
== 实验目的 ==

掌握带变长参数列表的函数

== 实验内容 ==

编写一个函数max(n, s1,s2,s3,...,sn)，计算求字符串s1,s2,s3...sn中最大的一个，n为参数个数

== 参考程序 ==

{{{#!cplusplus
#include <stdarg.h>

char *max(int n, ...) {
    char *maxstring = NULL;
    char * curr;
    va_list ap;
    
    va_start(ap, n);
    while(n-- > 0) {
        curr = va_arg(ap, char *);
        if(maxstring == NULL || strcmp(curr, maxstring) >0)
            maxstring = curr;    
    }
    return maxstring;
}
}}}

= 实验考试 =