C Primer Plus_第8章_字符输入输出和输入确认_编程练习

1.题略

#include <stdio.h>int main(void) {int ch,i=0;printf("Please enter text here(end with Ctrl + Z):\n");while (ch=getchar() != EOF)i++;printf("There are %d characters in text.\n", i);return 0; }

运行结果

输入第一个Ctrl+Z时，并没有结束，下一行再输入Ctrl+Z才检测到EOF。说明我的控制台环境下，文件结尾形式是一行的开始位置Ctrl+Z，而不是任意位置的Ctrl+Z。

 

2.题略

/* */ #include <stdio.h> int main(void) {int i=0, ch;while ((ch = getchar()) != EOF){if (ch == '\n')printf("\\n%3d \n",ch); //换行符就是一个字符，同时它提示读入行缓冲区中的数据else if (ch == '\t')printf("\\t%3d ",ch);else if ((ch < ' ') && (ch != '\n') && (ch != '\t'))printf("^%c%3d ",ch+64,ch);elseprintf("%-2c%3d ",ch,ch);i++;if(i%10 == 0)putchar('\n');} }

 

3.题略

/*统计大小字母个数*/ #include <stdio.h> #include <ctype.h>　　//关联函数isupper(),islower()int main(void) {int count_up = 0, count_low = 0;int count_other = 0;int ch;printf("Please enter some text: \n");while ((ch = getchar()) != EOF){if (isupper(ch))　　　　//isupper(ch)函数：ch是大写字母的话，函数返回真值1count_up++;else if (islower(ch))　//islower(ch)函数：ch是小写字母的话，函数返回真值1count_low++;elsecount_other++;}printf("There are %d upper letters\n", count_up);printf("and %d lower letters\n", count_low);printf("and %d other letters\n", count_other);return 0; }

运行结果

 

4.题略

/*报告单词中的字母数*/ #include <stdio.h> #include <ctype.h>int main(void) {int CountLet = 0, CountWrd =0;int ch, ch_pre=' ';printf("Please enter some text (ctrl+z to quit): \n");while ((ch = getchar()) != EOF){if (isalpha(ch))CountLet++;if ((isspace(ch) || ispunct(ch)) && isalnum(ch_pre))CountWrd++;ch_pre = ch;}printf("There are %d letters and %d words.\n", CountLet, CountWrd);printf("There are %d letters in a word on average.\n", CountLet / CountWrd);return 0; }

运行结果

 

5.题略

/*问大小后再猜数*/ #include <stdio.h> int main(void) {int min,max,mid,ch;printf("请输入被猜整数的范围：min（较小的数）和max（较大的数）\n");scanf("%d%d",&min,&max);printf("min = %d, max = %d\n",min, max);mid = min + (max-min)/2;printf("is it %d? (please enter y(yes), b(big), s(small))", mid);while((ch = getchar ()) != 'y'){if (ch == 'b'){max = mid;mid = min + (max-min)/2;printf("is it %d? (please enter y(yes), b(big), s(small))", mid);}else if (ch == 's'){min = mid;mid = min + (max-min)/2;printf("is it %d? (please enter y(yes), b(big), s(small))", mid);}else{if (ch == '\n')continue;elseprintf("Please just enter y, b, s.\n");}}printf("the number is %d!\n",mid);return 0; }

自己写的有点复杂了可能，不过运行起来还是可行的

 

6.题略

#include <stdio.h> #include <ctype.h>char get_first();int main(void) {printf("get_first() is %c", get_first()); }char get_first() {int ch;printf("Please enter some words:\n");while ((ch = getchar()) && (isspace(ch) == 0))continue;ch = getchar();return ch; }

8.题略

/**/ #include<stdio.h> #include<ctype.h> float get_float(void); char get_first(void);int main(void) {char select;float num1,num2;while(1){printf("Enter the operation of your choice:\n");printf("a.add s.subtract:\n");printf("m.multiply d.divide\n");printf("q.quit\n");select = get_first();if( select != 'a' && select != 's' && select != 'm' && select != 'd'){printf("Bye.\n");break;}printf("Enter first number:");num1 = get_float();printf("Enter second number:");num2 = get_float();while( select == 'd' && num2 == 0) {printf("Enter a number other than 0:");num2 = get_float();}switch(select){case 'a': printf("%.2f + %.2f = %.2f\n",num1, num2, num1 + num2); break;case 's': printf("%.2f - %.2f = %.2f\n",num1, num2, num1 - num2); break;case 'm': printf("%.2f * %.2f = %.2f\n",num1, num2, num1 * num2); break;case 'd': printf("%.2f / %.2f = %.2f\n",num1, num2, num1 / num2); break;default : break;}}return(0); }float get_float(void) //得到一个合适的浮点数，滤除非法数 {float num;char str[40];while(scanf("%f",&num)!=1){gets(str);printf("%s is not a number.\n",str);printf("Please enter a numbe, such as 2.5, -1.78E8, or 3:");}while ( getchar() != '\n');return num; }char get_first(void) //得到字符串中的第一个字符，滤除其他字符 {int ch;while( isspace( ch = getchar() ) );while ( getchar() != '\n');return ch; }

 

转载于:https://www.cnblogs.com/TomLily/p/5819384.html

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