本文介绍了简单C ++错误:“...未声明(首先使用此函数)的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我正在开始我的第一个C ++程序。由于某种原因,当我尝试编译它时,我得到以下错误:
p>
double truncate(double d);
double round(double d);
您可以在main之前定义函数,这将解决问题:
#include< iostream>
#include< math.h>
using namespace std;
#define CENTIMETERS_IN_INCH 2.54
#define POUNDS_IN_KILOGRAM 2.2
//舍入结果
双回合(双d){
回到楼层d + 0.5);
}
//舍入和截断到小数点后一位
double truncate(double d){
return round(double * 10)/ 10;
}
int main(){
...
}
Hey guys, I am working on my first C++ program for school. For some reason I am getting the following error when I try to compile it:
`truncate' undeclared (first use this function)Full Source:
#include <iostream> #include <math.h> using namespace std; #define CENTIMETERS_IN_INCH 2.54 #define POUNDS_IN_KILOGRAM 2.2 int main() { double feet, inches, centimeters, weight_in_kg, weight_in_lbs; // get height in feet and inches cout << "Enter height (feet): "; cin >> feet; cout << "Enter (inches): "; cin >> inches; // convert feet and inches into centimeters centimeters = ((12 * feet) + inches) * CENTIMETERS_IN_INCH; // round 2 decimal places and truncate centimeters = truncate(centimeters); printf("Someone that is %g' %g\" would be %g cm tall", feet, inches, centimeters); // weights for bmi of 18.5 weight_in_kg = truncate(18.5 * centimeters); weight_in_lbs = round(weight_in_kg * POUNDS_IN_KILOGRAM); printf("18.5 BMI would correspond to about %g kg or %g lbs", weight_in_kg, weight_in_lbs); // weights for bmi of 25 weight_in_kg = truncate(25 * centimeters); weight_in_lbs = round(weight_in_kg * POUNDS_IN_KILOGRAM); printf("25.0 BMI would correspond to about %g kg or %g lbs", weight_in_kg, weight_in_lbs); // pause output cin >> feet; return 0; } // round result double round(double d) { return floor(d + 0.5); } // round and truncate to 1 decimal place double truncate(double d) { return round(double * 10) / 10; }Any help would be appreciated. Thanks.
解决方案You need forward declaration before your main:
double truncate(double d); double round(double d);You could just define your functions before main, that will solve the problem too:
#include <iostream> #include <math.h> using namespace std; #define CENTIMETERS_IN_INCH 2.54 #define POUNDS_IN_KILOGRAM 2.2 // round result double round(double d) { return floor(d + 0.5); } // round and truncate to 1 decimal place double truncate(double d) { return round(double * 10) / 10; } int main() { ... }
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