C++ 数字常量前的预期 ',' 或 '...'
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expected ',' or '...' before numeric constant
提问by Patashu
I give up. Nor google answers me or the documentation. Whats wrong in here?
我放弃。谷歌也不回答我或文档。这里有什么问题吗？
" In file included from x.cpp:7: /Users/user/Dropbox/Projects/Arduino/libraries/Range/Range.h:27: error: expected identifier before numeric constant /Users/user/Dropbox/Projects/Arduino/libraries/Range/Range.h:27: error: expected ',' or '...' before numeric constant "
" 在 x.cpp:7 包含的文件中：/Users/user/Dropbox/Projects/Arduino/libraries/Range/Range.h:27: 错误：数字常量之前的预期标识符 /Users/user/Dropbox/Projects/Arduino/ libraries/Range/Range.h:27: 错误: 数字常量之前的预期 ',' 或 '...'
//
// Range.h
// Handles range to ground and altitude
//
// Created by x on 2013-03-27.
//
//
#ifndef RANGE_H_
#define RANGE_H_
#include "NewPing.h"
#define BOTTOM_RF_PIN 5
#define BOTTOM_RF_ECHO_PIN 10
#define BOTTOM_RF_MAX 200
class Range {
public:
Range();
void init();
float toGround();
float toCeiling();
float altitude();
private:
NewPing bottomRF(BOTTOM_RF_PIN, BOTTOM_RF_ECHO_PIN, BOTTOM_RF_MAX);
};
#endif /* RANGE_H_ */
回答by Patashu
Instead of
代替
NewPing bottomRF(BOTTOM_RF_PIN, BOTTOM_RF_ECHO_PIN, BOTTOM_RF_MAX);
NewPing bottomRF(BOTTOM_RF_PIN, BOTTOM_RF_ECHO_PIN, BOTTOM_RF_MAX);
Try
尝试
NewPing bottomRF(int, int, int);
NewPing bottomRF(int, int, int);
Reason: You cannot declare a function to take literals. Only types. intis a type, 5 10 and 200 are literals.
原因：您不能声明一个函数来接受文字。只有类型。int是一种类型，5 10 和 200 是文字。
回答by Tushar
In case bottomRFis a data member, and not a function, and you are trying to instantiate it in the class declaration:
如果bottomRF是数据成员而不是函数，并且您试图在类声明中实例化它：
You cannot instantiate class-type items in the class declaration. A good place to do so is in the constructor initialization list.
您不能在类声明中实例化类类型项。这样做的好地方是在构造函数初始化列表中。
public:
Range() :bottomRF(BOTTOM_RF_PIN, BOTTOM_RF_ECHO_PIN, BOTTOM_RF_MAX) {}
回答by Archer
Don't you need to specify the type of parameters? e.g.
不需要指定参数的类型吗？例如
NewPing bottomRF(int a1 = BOTTOM_RF_PIN, int a2= BOTTOM_RF_ECHO_PIN, int a3 = BOTTOM_RF_MAX);
