功能完备c++计算器11

#include #include #include #include using namespace std; enum types DELIMITER = 1, VARIABLE, NUMBER; /定义枚举类型把DELIMITER初试化为后面的相应的是前面值+1 int error_type = -1;class calculator char *cal_p; / 定义一个指向表达式的指针char token80; / 存储表达式中的字符变量char tok_type; / 存储具体是什么类型void cal_p2(double void cal_p3(double void cal_p4(double void cal_p5(double void cal_p6(double void atom(double /把字符串转换为浮点数void get_token(); /取得下一个字符void error(int err); /显示打印出错信息int isdelim(char c); /判断是否为分隔符public: calculator();/类的构造函数double cal(char *exp); int error_type; / 存储错误信息; / 类构照函数的具体实现calculator:calculator() cal_p = NULL;/把exp_ptr的指针初始化为空error_type = -1; / 方法eval_exp的具体实现过程double calculator:cal(char *p) double result; cal_p = p;/把传递过来的参数p赋给cal_pget_token(); if(!*token) error(2); /输出没有任何表达式的错误信息return 0.0; cal_p2(result); if(*token)error(0); / last token must be null return result; / 两个变量字符是加或者减操作void calculator:cal_p2(double double temp; cal_p3(result); while(op = *token) = +|op = -) get_token(); cal_p3(temp); switch(op) case -: result = result - temp; break; case +: result = result + temp; break; / 两个变量是乘或者除操作或者是取余void calculator:cal_p3(double double temp; cal_p4(result); while(op = *token) = * |op = / | op = %) get_token(); cal_p4(temp); switch(op) case *: result = result * temp; break; case /:if (temp = 0)error(3);else result = result / temp; /除数为零的情况要考虑进去break; case %: result = (int) result % (int) temp; break; / 进行运算void calculator:cal_p4(double register int t; cal_p5(result); if(*token= ) get_token(); cal_p4(temp); ex = result; if(temp=0.0) result = 1.0; return; for(t=(int)temp-1; t0; -t) result = result * (double)ex; void calculator:cal_p5(double op = 0; if(tok_type = DELIMITER) get_token(); cal_p6(result); if(op=-) result = -result; / 进行有括号的算法void calculator:cal_p6(double cal_p2(result); if(*token != ) error(1); get_token(); else atom(result); / 取得数值void calculator:atom(double /atof()把字符串转换成浮点数double atof( const char *str );get_token(); return; default: error(0); / 输出出错信息. void calculator:error(int err) error_type = err;static char *e= “语法错误！请核对后重新输入“, “缺少一个括号！请核对后再输入“, “您没有输入任何表达式！“,“除数不能为！请核对后重新输入“; cout 若参数c为空格字符，则返回TRUE，否则返回NULL(0)if(strchr(“+-*/%=()“, *cal_p) /用strchr函数在字符串“+-*/%=()“中查找*exp_ptr指向的字符所在位置，判断返回值(非为真就执行)以便是否执行以下语句tok_type = DELIMITER;/把tok_type置为DELIMITER / advance to next char *temp+ = *cal_p+; else if(isalpha(*cal_p) /当参数c为大写英文字母(A-Z)时，返回非零值，否则返回零while(!isdelim(*cal_p) *temp+ = *cal_p+; /isdelim判断是否是分隔符，当*exp_ptr指向的字符不为分隔符时把值赋给*temp tok_type = VARIABLE;/把tok_type置为VARIABLE else if(isdigit(*cal_p) / isdigit判断*exp_ptr指向的字符是否为数字while(!isdelim(*cal_p) *temp+ = *cal_p+; /isdelim判断是否是分隔符，当*exp_ptr指向的字符不为分隔符时把值赋给*temptok_type = NUMBER; *temp = 0; /空格 / isdelim函数的具体实现，如果参数是一个分隔符则返回真int calculator:isdelim(char c) if(strchr(“ +-/*%=()“, c) /把“+-/*%=()09r定义非分隔符,/r回车return 1; return 0; /strchr(const char *s,char c),返回首次出现c的位置的指针，如果s中不存在c则返回NULL。int main() char calchar80; calculator ob; / 创建一个calculator类型的实例double result;for(;) cout “请输入你要计算的表达式: “endl; ci