93 lines
2.6 KiB
C++
93 lines
2.6 KiB
C++
#include <iostream>
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#include <cstdlib>
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#include <cstring>
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#include <cmath>
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#include "calc.hh"
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static int pos = 0;
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void calc_reset(){
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pos = 0;
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}
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double calc_factor_value(const char * factor){
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double result1 = 0.0, result2 = 0.0, final_result = 0.0;
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char c = factor[pos];
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if( c == '('){ // if expression has '(', calculate the expression in the '()'
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pos++; // Pass the '('
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result1 = calc_expression_value(factor);
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pos++; // Pass the ')'
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}else{
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while(isdigit(c)){ // Get the number to calculate
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result1 = 10 * result1 + c - '0';
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pos++;
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c = factor[pos];
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}
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if(c == '.'){ // Get number between 0 to 1
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pos++; // Pass the '.'
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c = factor[pos];
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while(isdigit(c)){
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result2 = 0.1 * result2 + (c - '0') * 0.1;
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pos++;
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c = factor[pos];
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}
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}
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final_result = result1 + result2;
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if(c == '%'){
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final_result /= 100.0; // Pass the '%'
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pos++;
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}
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}
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return final_result;
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}
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double calc_term_value(const char * term){
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double result = calc_factor_value(term); // Get the first number
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double value = 0.0;
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while(pos < strlen(term)){
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//pos++; // Calc the multiplication and divide
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char op = term[pos];
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if(op == '^' || op == '*' || op == '/'){
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switch (op)
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{
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case '^':
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pos++;
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value = calc_factor_value(term); // Pow
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result = pow(result,value);
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break;
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case '*':
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pos++;
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value = calc_factor_value(term); // Subb
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result *= value;
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break;
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case '/':
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pos++;
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value = calc_factor_value(term); // Get another value
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result /= value;
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break;
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}
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break;
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}else{
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break;
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}
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}
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return result;
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}
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double calc_expression_value(const char * expression){
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double result = calc_term_value(expression); // Calc the result of expression
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//bool more = true;
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while(pos < strlen(expression)){
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char op = expression[pos];
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if(op == '+' || op == '-'){ // Calculate for add and subb
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pos++;
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double value = calc_term_value(expression);
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if( op == '+') result += value;
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else result -= value;
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}else{
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break;
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}
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}
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return result;
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}
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