C程序设计（第二版 新版）第一章 习题

-2.空格串替换为最少量的制表符和空格，保持单词之间的间隔不变。

#include<stdio.h>#define BASIC  8int main(){freopen("Example.in","r",stdin);int nb,nt,c;int pos;for(pos = 1,nb = nt = 0; (c = getchar()) != EOF; ++pos){if(c == ' '){if(pos % BASIC)++nb;else{nb = 0;++nt;}}else{while(nt){putchar('\t');--nt;}if(c == '\t')nb = 0;while(nb){putchar(' ');--nb;}if(c == '\n')pos = 0;else if(c == '\t')pos = pos -1 + (BASIC - (pos - 1) % BASIC);putchar(c);}}return 0;}

-1.删除每个输入末尾的空格及制表位，并删除完全是空格的行。

#include<stdio.h>#define MAXLINE 1000int getline(char line[], int maxline);void copy(char to[], char from[]);FILE *fp;int main(){fp = fopen("Example.in","r");if(!fp)return 1;int len;char line[MAXLINE];while((len = getline(line,MAXLINE))> 0)if(len >= MAXLINE)printf("%s",line);else if(remove(line,len) > 0)printf("%s",line);fclose(fp);return 0;}int getline(char line[],int lim){int i;int c;for(i = 0; i < lim -1 && (c = fgetc(fp))!= EOF && c != '\n'; ++i)line[i] = c;if(c == '\n')line[i++] = c;line[i] = '\0';return i;}int remove(char line[],int len){int i = len - 2;while(i >= 0 && (line[i] == ' ' || line[i] == '\t'))--i;if(i >= 0){line[++i] = '\n';line[++i] = '\0';}return i;}

 

0.单词计数（例1.5.4）

#include<stdio.h>#define OUT 1  /*  在单词内 */#define IN  0  /*  在单词外 */int main(){int c,nl,nw,nc,state;state = OUT;nl = nw = nc = 0; // nl:行数 nw:单词数  nc：字符数   while((c = getchar()) != EOF){++nc;if(c == '\n')++nl;if(c == ' ' || c == '\t' || c == '\n')state = OUT;else if(state == OUT){state = IN;++nw;}}printf("%d %d %d\n",nl,nw,nc);return 0;} 

 

1. 打印输入单词长度的水平和数值直方图

#include<stdio.h>#define IN      1#define OUT     0#define MAXHIST  21  /* max  length of histogram*/ int main(){    int i,j,nc,maxvalue,state,len;    int c;    int wl[MAXHIST];/* wl[i] 的值表示长度为i的单词的数量*/    for(i =1; i < MAXHIST; i++)    wl[i] = 0;    state = OUT;        nc = 0;    while( (c = getchar()) != EOF)    {        if( c == ' ' || c == '\n' || c == '\t')        {            state = OUT;            if( nc > 0)                wl[nc] ++;            nc = 0;        }        else if( state == OUT)        {            state = IN;            nc ++;        }        else            nc ++;  }/*输出水平直方图*/for(i = 1; i < MAXHIST; i++){    if(wl[i] > 0)        len = wl[i];    else        len = 0;    printf("%2d - %2d :", i,len );    while( len-- > 0)        putchar('*');    putchar('\n');}putchar('\n');/* 找出单词数量出现最大值*/maxvalue = 0;for( i = 1; i < MAXHIST; i++)if( maxvalue < wl[i])maxvalue = wl[i];/*水平输出直方图*/for( i = maxvalue; i > 0; i--){    for(j = 1; j < MAXHIST; j++ )    if( wl[j] >= i)        printf(" * ");    else        printf("   ");    putchar('\n');}for(i = 1; i < MAXHIST; i++)printf("%2d ",i);putchar('\n');for(i = 1; i < MAXHIST; i++)   printf("%2d ",wl[i]);putchar('\n');getchar();return 1;}

 

2.把较长的输入行"拆"成短一些的两行或多行，折行的位置在第n列之前的最后一个非空格之后（注意空格和制表符）（c程序设计语言 1-22题 ）

#include<stdio.h>#define TABINC       8#define MAXCOL       10char line[MAXCOL];void printl(int pos){    int i;    for(i=0; i < pos; i++)    {     putchar(line[i]);    }    if(pos > 0)     putchar('\n');}int exptab(int pos){    int i;    while(pos < MAXCOL && pos % TABINC != 0)    {               line[pos]=' ';    pos ++;    }    if( pos >= MAXCOL)    {        printl(MAXCOL);        return 0;    }    else        return pos;}int findblnk(int pos){    int i = pos;    while( i >= 0 && line[i] != ' ')    {    i --;    }    if( i < 0)        return MAXCOL;    else        return i+1;}int newpos(int pos){    if( pos <= 0 || pos >= MAXCOL)        return 0;    else    {        int i;        for(i=0; pos < MAXCOL; i++,pos++)                 line[i] = line[pos];        return i;    }}int main(){    int c, pos;        pos = 0;    while((c = getchar()) != EOF)    {    line[pos] = c;     if( c == '\t')      {        pos = exptab(pos);      }      else if( c == '\n')      {          printl(pos);        pos = 0;      }      else if( ++pos >= MAXCOL)      {          pos = findblnk(pos - 1);          printl(pos);          pos = newpos(pos);      }     }    getchar();    return 1;}

3.删除c语言中的所有注释，正确处理引号中的字符串和字符常量。（1-23）

#include<stdio.h>void rcomment(int c);void in_comment(void);void out_comment(void);void echo_quote(int c);int main(){    int c;    while((c = getchar()) != EOF)    {          // printf("recomment-in\n");             rcomment(c);          // printf("recomment-out\n");    }    getchar();    return 1;}void rcomment(int c){     int d;     if( c == '/')     {         d = getchar();         if(d == '*')         {              in_comment();         }         else if( d == '/')         {              out_comment();         }         else         {             putchar(c);             putchar(d);         }     }     else if( c == '\'' || c == '\"')     {         echo_quote(c);     }     else         putchar(c);}void in_comment(void){     int c ,d;     c = getchar();     d = getchar();     while(c != '*' || d != '/')     {             c = d;             d = getchar();     }}void out_comment(void){     int c;     while( (c = getchar()) != '\n');     putchar(c);}void echo_quote(int c){     int d;     while( (d = getchar()) != c)     {            putchar(d);            if( d == '\\')                putchar(getchar());     }     putchar(d);}

 

4. 查找c语言中的基本语法错误，如圆括号、方括号、花括号不配对等。要正确处理引号（包括单引号和双引号）、转义字符序列与注释（1-24）

#include<stdio.h>int brace,brack,paren;void in_comment();void out_comment();void in_quote();void search(int);int main(){freopen("test.in","r",stdin);int c;while((c = getchar()) != EOF){if(c == '/'){int d = getchar();if(d == '*')in_comment();else if(d == '/')out_comment();elsesearch(d);}else if(c == '\'' || c == '\"')in_quote(c);elsesearch(c);if(brace < 0){puts("Unbalanced braces");brace = 0;}if(brack < 0){puts("Unbalanced bracks");brack = 0;}if(paren < 0){puts("Unbalanced parens");paren = 0;}}if(brace > 0)puts("Unbalanced braces");if(brack > 0)puts("Unbalanced bracks");if(paren > 0)puts("Unbalanced parens");return 0;}void in_comment(){int c = getchar();int d = getchar();while(c != '*' || d != '/'){c = d;d = getchar();}}void out_comment(){int c;while((c = getchar()) != '/n' && c != EOF);}void in_quote(int c){int d;while((d = getchar()) != c){if(d == '\\')getchar();}}void search(int c){switch(c){case '{':++brace;break;case '}':--brace;break;case '[':++brack;break;case ']':--brack;break;case '(':++paren;break;case ')':--paren;break;}}