[英]Passing std::ofstream object as argument to class method
正如前面的問題已得到回答一樣,將std::ofstream
對象作為函數參數傳遞的方式似乎是傳遞引用: std::ofstream&
。
在編譯此解決方案的同時,結果輸出並不等同於在方法內創建std :: ofstream對象,然后調用write()。
以下代碼未提供正確的輸出:
在main.cpp中 :
std::ofstream file(path + "output.stubs");
stub->writeRaw(file); //stub is a pointer to an object of class Stub
file.close();
在Stub.cpp中 :
void Stub::writeRaw(std::ofstream& file) {
file.write((char*)this, sizeof(*this));
}
通過將Stub.cpp都更改為以下內容,可以提供正確的輸出:
void Stub::writeRaw(void) {
std::ofstream file(path + "output.stubs");
file.write((char*)this, sizeof(*this));
file.close();
}
或將對象寫入main中的文件中,而不是調用類方法。
對此行為的任何幫助將不勝感激!
編輯
類Stub的一些上下文:
Stub.hpp
#pragma once
#include <iostream>
#include <ios>
#include <fstream>
#include "constants.hpp"
#include "DataTypes.hpp"
class Stub {
private:
StubHeader header;
StubIntrinsicCoordinates intrinsic;
StubPayload payload;
public:
Stub(void);
virtual ~Stub(void);
StubHeader getHeader(void);
StubIntrinsicCoordinates getIntrinsicCoordinates(void);
StubPayload getPayload(void);
void setHeader(StubHeader stub_header);
void setIntrinsicCoordinates(StubIntrinsicCoordinates stub_intrinsic);
void setPayload(StubPayload stub_payload);
void print(void);
void writeRaw(std::ofstream& file);
};
以及相關的數據類型定義如下:
struct StubHeader {
uint8_t bx;
uint8_t nonant;
};
struct StubIntrinsicCoordinates {
uint8_t strip;
uint8_t column;
int crossterm;
};
struct StubPayload {
bool valid;
int r;
int z;
int phi;
int8_t alpha;
int8_t bend;
uint8_t layer;
bool barrel;
bool module;
};
編輯2
讀取存根的(玩具)代碼如下:
std::ifstream r(path + "output.stubs");
Stub s;
r.read((char*)&s, sizeof(s));
s.print();
僅一個存根被寫入文件,因為這是對功能的測試。 Stub類的打印功能如下:
void Stub::print(void) {
std::cout << "----- Header -----" << '\n';
std::cout << "bx: " << std::dec << (int)header.bx << '\n';
std::cout << "nonant: " << std::dec << (int)header.nonant << '\n';
std::cout << "----- Intrinsic Coordinates -----" << '\n';
std::cout << "strip: " << std::dec << (int)intrinsic.strip << '\n';
std::cout << "column: " << std::dec << (int)intrinsic.column << '\n';
std::cout << "crossterm: " << std::dec << (int)intrinsic.crossterm << '\n';
std::cout << "----- Payload -----" << '\n';
std::cout << "valid: " << std::boolalpha << payload.valid << '\n';
std::cout << "r: " << std::dec << (int)payload.r << '\n';
std::cout << "z: " << std::dec << (int)payload.z << '\n';
std::cout << "phi: " << std::dec << (int)payload.phi << '\n';
std::cout << "alpha: " << std::dec << (int)payload.alpha << '\n';
std::cout << "bend: " << std::dec << (int)payload.bend << '\n';
std::cout << "layer: " << std::dec << (int)payload.layer << '\n';
std::cout << "barrel: " << std::boolalpha << payload.barrel << '\n';
std::cout << "module: " << std::boolalpha << payload.module << "\n\n";
}
編輯3
為了完整性和透明度,請在下面找到main.cpp的確切代碼:
int main(int argc, char const *argv[]) {
Geometry g;
g.generateModuleLUTs();
g.generateCorrectionLUTs();
std::vector<std::array<Stub*, PAYLOAD_WIDTH> > all_stubs;
std::vector<Module> modules = g.getData();
for (int i = 0; i < LINK_NUMBER; i++) {
LinkGenerator link_gen;
LinkFormatter link_formatter(link_gen.run());
StubFormatter stub_formatter(link_formatter.run(), i);
std::array<Stub*, PAYLOAD_WIDTH> stubs = stub_formatter.run(modules);
CoordinateCorrector coordinate_corrector(stubs);
all_stubs.push_back(coordinate_corrector.run());
}
std::ofstream f(path + "output.stubs");
all_stubs[0][0]->writeRaw(f);
all_stubs[0][0]->print();
std::ifstream r(path + "output.stubs");
Stub s;
r.read((char*)&s, sizeof(s));
s.print();
return 0;
}
代碼中的錯誤是在構造std::ifstream
對象以再次讀取文件之前,我沒有調用file.close()
。 這是意外行為的原因。
寫一個類文件中使用this
似乎是有效的,但你是細心,知道你要寫入文件究竟什么是重要的。
感謝所有發表評論並幫助回答此問題的人!
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