所以我有这部分代码工作得很好。然后我添加了一些行(它下面的代码),现在它在执行时崩溃了。从我做的测试,它似乎陷入了while循环..我是一个新手,我不知道这些变化是如何影响而
编辑:程序编译没有错误。 执行时会出现此消息: 此应用程序已请求Runtime以不寻常的方式终止它。 现在它不会让我使用调试器......(我正在使用Dev C ++)
int main() {
char fileName[] = "espion.txt";
std:: string infoEspion;
Espion *cur = 0, *first = 0, *last = 0, *add = 0;
std :: ifstream readFile;
readFile.open(fileName, std::ios::in);
if(!readFile.is_open())
exit(EXIT_FAILURE);
while(std::getline(readFile, infoEspion)) {
if(first == NULL){ //head
add = new Espion;
add -> name = infoEspion.substr(0,30);
add -> next = NULL;
first = add;
cur = add;
last = add;
} else if(findName(first, infoEspion.substr(0,30)) == NULL ) {
// adding only if not on the list already
add = new Espion;
add -> name = infoEspion.substr(0,30);
add -> next = NULL;
cur -> next = add;
last = add;
cur = add;
}
}
printList(first);
printList(sortAlpha(first));
readFile.close();
system("pause");
return 0;
}
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
#include <cerrno>
struct Pays
{
std:: string name; /* nom du pays */
Pays *next; /* pointeur sur le prochain pays */
};
struct Espion
{
std:: string name; /* nom de l’espion(ne) */
Espion *next; /* pointeur sur le prochain espion */
Pays *begListPays; /* tête de liste des pays visités */
Pays *endListPays;
};
Espion *findName(Espion* ptr, std::string nameToCompare)// returns pointer or NULL
{
while (ptr)
{
if(ptr->nom.compare(nameToCompare) == 0)
return ptr;
ptr = ptr->next;
}
ptr = NULL;
return ptr;
}
int main() {
char fileName[] = "espion.txt";
std:: string infoEspion;
Espion *cur = 0, *first = 0, *last = 0, *add = 0, *curP = 0;
Pays *firstP = 0, *lastP = 0, *addP = 0;
std :: ifstream readFile;
readFile.open(fileName, std::ios::in);
if(!readFile.is_open())
exit(EXIT_FAILURE);
while(std::getline(readFile, infoEspion)) {
if(first == NULL){ //head
add = new Espion;
add -> name = infoEspion.substr(0,30);
add -> next = NULL;
first = add;
cur = add;
last = add;
addP = new Pays;
addP-> name = infoEspion.substr(30,20);
addP-> next = NULL;
add-> begListPays = addP;
add-> endListPays = addP;
//changes up to here run OK!
} else if(findName(first, infoEspion.substr(0,30)) == NULL ) {
// adding only if not on the list already
add = new Espion;
add -> name = infoEspion.substr(0,30);
add -> next = NULL;
cur -> next = add;
last = add;
cur = add;
addP = new Pays;
addP->name = infoEspion.substr(30,20);
addP->next = NULL;
add->begListPays = addP;
add->endListPays = addP;
} else {
addP = new Pays;
addP-> name = infoEspion.substr(30,20);
addP-> next = NULL;
findName(first, infoEspion.substr(0,30))->endListPays->next = addP;
findName(first, infoEspion.substr(0,30))->endListPays = addP;
}
}
printList(first);
printList(sortAlpha(first));
readFile.close();
system("pause");
return 0;
}
答案 0 :(得分:0)
如果文件以换行符结束,那么while
循环没有考虑最后一行是空的,因此substr(30,20)
会引发异常。
此外,您的循环代码有不必要的代码重复。您可以大大简化逻辑。
试试这个:
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
#include <cerrno>
#include <string>
struct Pays
{
std::string name; /* nom du pays */
Pays *next; /* pointeur sur le prochain pays */
};
struct Espion
{
std::string name; /* nom de l’espion(ne) */
Espion *next; /* pointeur sur le prochain espion */
Pays *begListPays; /* tête de liste des pays visités */
Pays *endListPays;
};
Espion* findName(Espion* ptr, std::string nameToCompare)// returns pointer or NULL
{
while (ptr)
{
if(ptr->name.compare(nameToCompare) == 0)
return ptr;
ptr = ptr->next;
}
return NULL;
}
int main()
{
char fileName[] = "espion.txt";
std::string infoEspion, espionName, paysName;
Espion *first = 0, *last = 0, *add;
Pays *addP;
std::ifstream readFile;
readFile.open(fileName, std::ios::in);
if (!readFile.is_open())
exit(EXIT_FAILURE);
while (std::getline(readFile, infoEspion))
{
if (infoEspion.empty())
continue;
espionName = infoEspion.substr(0,30);
paysName = infoEspion.substr(30,20);
add = findName(first, espionName);
if (!add)
{
add = new Espion;
add->name = espionName;
add->next = NULL;
add->begListPays = NULL;
add->endListPays = NULL;
if (!first) first = add;
if (last) last->next = add;
last = add;
}
addP = new Pays;
addP->name = paysName;
addP->next = NULL;
if (!add->begListPays) add->begListPays = addP;
if (add->endListPays) add->endListPays->next = addP;
add->endListPays = addP;
}
printList(first);
printList(sortAlpha(first));
readFile.close();
system("pause");
return 0;
}
话虽如此,您应该利用为您管理更多逻辑的C ++功能:
#include <iostream>
#include <fstream>
#include <cstdlib>
#include <cstring>
#include <cstdio>
#include <cerrno>
#include <string>
#include <list>
#include <algorithm>
struct Pays
{
std::string name; /* nom du pays */
};
struct Espion
{
std::string name; /* nom de l’espion(ne) */
std::list<Pays> ListPays; /* tête de liste des pays visités */
bool operator<(const Espion& rhs) const
{
return (name < rhs.name);
}
};
struct isEspionName
{
std::string _name;
isEspionName(const std::string &nameToCompare) : _name(nameToCompare) {}
bool operator()(const Espion& e) const
{
return (e.name == _name);
}
};
int main()
{
char fileName[] = "espion.txt";
std::string infoEspion, espionName, paysName;
std::list<Espion> ListEspion;
Espion *e;
std::ifstream readFile;
readFile.open(fileName, std::ios::in);
if (!readFile.is_open())
exit(EXIT_FAILURE);
while (std::getline(readFile, infoEspion))
{
if (infoEspion.empty())
continue;
espionName = infoEspion.substr(0,30);
paysName = infoEspion.substr(30,20);
std::list<Espion>::iterator iter = std::find_if(ListEspion.begin(), ListEspion.end(), isEspionName(espionName));
if (iter != ListEspion.end())
{
e = &(*iter);
}
else
{
Espion addE;
addE.name = espionName;
ListEspion.push_back(addE);
e = &(ListEspion.back());
}
Pays addP;
addP.name = paysName;
e->ListPays.push_back(addP);
}
readFile.close();
printList(ListEspion);
ListEspion.sort();
printList(ListEspion);
system("pause");
return 0;
}
std::list
是作为双重链接列表实现的。如果您确实需要单链接列表,C ++ 11会在std::forward_list
中添加#include <forward_list>
类。