C程序设计语言 4-10

练习4-10 另一种方法是通过getline函数读入整个输入行，这种情况下可以不使用getcha和ungetch函数。请运用这一方法修改计算器程序。

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include "calc.h"#define MAXLEN 100
#define MAXOP 100int getop(char s[], char t[]);
void push(double);
double pop(void);int main()
{int type;double op1, op2;char s[MAXOP];char t[MAXOP];    //增加字符串t作为switch循环体中的返回值，字符串s仅仅储存每一行的输入while ((type = getop(s, t)) != EOF){switch (type) {case NUMBER:push(atof(t));break;case '+':push(pop() + pop());break;case '*':push(pop() * pop());break;case '-':op2 = pop();push(pop() - op2);break;case '/':op2 = pop();if (op2 != 0.0)push(pop() / op2);elseprintf("error:zero divisior\n");break;case '\n':printf("result: %.8g\n", pop());break;default:printf("error: unknown command %s\n", s);break;}}return 0;
}

#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include "calc.h"void getline(char s[]);int getop(char s[], char t[])
{int i, c;char clear[] = "";    //添加清空字符串的功能getline(s);strcpy(t, clear);	//初始化字符串ti = 0;if (!isdigit(s[i]) && !islower(s[i]) && s[i] != '.')return (c = s[i]);i = 0;if (isdigit(t[i++] = s[i]))while (isdigit(t[i++] = s[i]));if ((t[i++] = s[i]) == '.')while (isdigit(t[i++] = s[i]));t[i] = '\0';return NUMBER;
}

#include <stdio.h>
#include <string.h>
#define MAXVAL 100int sp = 0;
double val[MAXVAL];void push(double f)
{if (sp < MAXVAL)val[sp++] = f;elseprintf("error: stack full, can't push %g\n", f);return;
}double pop(void)
{if (sp > 0)return val[--sp];else{printf("error:stack empty\n");return 0.0;}
}

#include <stdio.h>
#include <string.h>
#include "calc.h"
#define MAXLEN 100void getline(char s[])
{int c, i;char clear[] = "";    //添加清空字符串的功能strcpy(s, clear);while ((c = getchar()) == ' ' || c == '\t');s[0] = c;for (i = 1; i < MAXLEN && (c = getchar()) != EOF && c != '\n'; i++)s[i] = c;if (c == '\n')s[i] = '\n';++i;return;
}

#define NUMBER '0'
#define ERROR '1'void push(double);
double pop(void);
int getop(char s[], char t[]);
void getline(char s[]);