我刚开始用c ++编程(IDE是CodeBlocks)。
我写了两个简单的类(Song和Metadata)并使用sqlite进行测试。
问题:我的程序似乎内存不足:当我启动程序时,它会立即崩溃,或者sqlite3_open命令返回错误“内存不足”。当我在没有任何其他代码的情况下测试SQLITE函数时,它可以工作!
所以这不起作用:
#include <iostream>
#include "metadata.h"
#include "Song.h"
#include <cstdio>
#include "sqlite3.h"
using namespace std;
int main()
{
// Without this block it DOES work!
Metadata* tmpMeta = new Metadata("Eiffel 65", "Blue", "Europop");
Song* tmpSong;
tmpSong = new Song();
tmpSong->set_metadata(*tmpMeta);
// end of block
sqlite3 *db;
int rc;
rc = sqlite3_open_v2("test.db", &db, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, NULL);
cout << "Result: " << sqlite3_errmsg(db) << '\n';
sqlite3_close(db);
return 0;
}
请参阅随附的歌曲和元数据类。
我不知道如何应对这个错误。
我的环境: - Windows 8,64位 - Code :: Blocks 10.05 - 编译器:GNU GCC编译器
提前谢谢!
问候 塞巴斯蒂安
Song.h:
#include <iostream>
#include <cstring>
#include "metadata.h"
using namespace std;
class Song {
private:
Metadata metadata;
unsigned int iD;
char filename[400];
public:
//Constructors
Song( Metadata, unsigned int, const char*);
Song( );
//Methods
void set_metadata(Metadata& meta);
void set_id(unsigned int i);
void set_filename(const char* f);
Metadata get_metadata();
unsigned int get_id();
const char* get_filename();
};
Song.cpp:
#include <iostream>
#include "Song.h"
using namespace std;
Song::Song(Metadata m, unsigned int id, const char* f) {
metadata = m;
iD = id;
strncpy(filename, f, sizeof(filename)-1);
filename[sizeof(filename)] = '\0';
}
Song::Song( ) {
Metadata tmpMeta;
metadata = tmpMeta;
iD = 0;
strncpy(filename, "unknown", sizeof(filename) -1);
filename[sizeof(filename)] = '\0';
}
void Song::set_filename(const char* f) {
strncpy( filename, f, sizeof(filename)-1 );
filename[sizeof(filename)] = '\0';
}
void Song::set_id(unsigned int i) {
iD = i;
}
void Song::set_metadata(Metadata& meta) {
metadata = meta;
}
Metadata Song::get_metadata() {
return metadata;
}
const char* Song::get_filename() {
return filename;
}
unsigned int Song::get_id() {
return iD;
}
Metadata.h:
#include <iostream>
#include <cstring>
#ifndef _METADATA_H_
#define _METADATA_H_
using namespace std;
class Metadata {
private:
unsigned int trackNumber;
char artist[20];
char title[20];
unsigned int year;
char genre[20];
char album[20];
public:
Metadata(const char*, const char*, const char*);
const char* get_artist();
const char* get_title();
const char* get_album();
const char* get_genre();
unsigned int get_trackNumber();
unsigned int get_year();
void set_artist(const char*);
void set_title(const char*);
void set_album(const char*);
void set_genre(const char*);
void set_year(unsigned int);
void set_trackNumber(unsigned int);
};
#endif
Metadata.cpp:
#include <iostream>
#include "metadata.h"
Metadata::Metadata(const char* ar, const char* tit, const char* al) {
trackNumber = 0;
year = 0;
strncpy(genre, "unknown", sizeof(genre) -1);
genre[sizeof(genre)] = '\0';
strncpy(artist, ar, sizeof(artist) -1);
artist[sizeof(artist)] = '\0';
strncpy(title, tit, sizeof(title) -1);
title[sizeof(title)] = '\0';
strncpy(album, al, sizeof(album) -1);
album[sizeof(album)] = '\0';
}
const char* Metadata::get_artist() {
return artist;
}
const char* Metadata::get_title() {
return title;
}
const char* Metadata::get_album() {
return album;
}
const char* Metadata::get_genre() {
return genre;
}
void Metadata::set_artist(const char* ar) {
strncpy(artist, ar, sizeof(artist) -1);
artist[sizeof(artist)] = '\0';
}
void Metadata::set_title(const char* tit) {
strncpy(title, tit, sizeof(title) -1);
title[sizeof(title)] = '\0';
}
void Metadata::set_album(const char* al) {
strncpy(album, al, sizeof(album) -1);
album[sizeof(album)] = '\0';
}
void Metadata::set_genre(const char* g) {
strncpy(genre, g, sizeof(genre) -1);
genre[sizeof(genre)] = '\0';
}
void Metadata::set_trackNumber(unsigned int tn) {
trackNumber = tn;
}
void Metadata::set_year(unsigned int y) {
year = y;
}
答案 0 :(得分:1)
对于初学者:所有您的字符串终止代码在Metadata.cpp和Song.cpp中是错误的:
示例:强>
strncpy(genre, "unknown", sizeof(genre) -1);
genre[sizeof(genre)] = '\0';
对strncpy()的调用是正确的。硬终结者不是。它应该是:
strncpy(genre, "unknown", sizeof(genre) -1);
genre[sizeof(genre) -1] = '\0';
这会在所有字符串上复制。重新检查他们。它会表现出几种副作用,直到你修复它们为止。考虑到这些对象都是堆分配的,你就会在Song::filename[]
和MetaData::albumin[]
的不当终止时破坏你的堆。不要只修复那两个; 解决所有问题。
记住。 sizeof()
返回传递的字段的八位字节数。这意味着char field[N];
将返回N
。如果您已经了解C / C ++,那么您知道数组是从零开始的,因此field[N-1]
是最大允许索引。