Fatest Way Around
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Hi everyone, I need advice regardin my problem, here's my problem: I have a Text File(serves as my database) with 3 colums fixed length, example Name Address Age AAA 123 Anywhere 12 BBB .... ... Joseph 345 Somewhere 15 Rosie 098 Cool DC 20 I need to search this Text File, in the real world this Text File migh contain 1 Million records as soon as we populate our database. My question is... what is the fastest way to search for a particular string in this text file. Note: I only search for the name, If I find the name... I need to get the enrite line and process it. I will really appreciate any help that you can give me. Thanks/Regards Sidney
I will give you a fast, but memeory consuming solution. Use a std::map to store the name as keys and you make a struct to store the address. Read the whole file and fill the map. Then, when you search the name you will use std::map::find that will do a binary search. At the end of the program you iterate through the map and write it to the file. If you have multiple entries with the same name you may consider multimap. Since you post it to the Manage C++ you may also consider hash_map. Best regards, Alexandru Savescu
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Thanks Alexandru! I'll see if I can do this, do you have sample code that used STL Map? if you have would you be so kind to share it with me? And by the way just for info... the fields are of Fixed length, example Field Name Position Length Fld1 1 10 Fld2 11 21 etc... Thanks/Regards Sidney
You can look at the article on CP about STL here. Also you can read MSDN (the one that comes with .NET is nicer than the VC6.0's one), or the SGI documentation. Best regards, Alexandru Savescu
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I will give you a fast, but memeory consuming solution. Use a std::map to store the name as keys and you make a struct to store the address. Read the whole file and fill the map. Then, when you search the name you will use std::map::find that will do a binary search. At the end of the program you iterate through the map and write it to the file. If you have multiple entries with the same name you may consider multimap. Since you post it to the Manage C++ you may also consider hash_map. Best regards, Alexandru Savescu
Thanks Alexandru! I'll see if I can do this, do you have sample code that used STL Map? if you have would you be so kind to share it with me? And by the way just for info... the fields are of Fixed length, example Field Name Position Length Fld1 1 10 Fld2 11 21 etc... Thanks/Regards Sidney
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I will give you a fast, but memeory consuming solution. Use a std::map to store the name as keys and you make a struct to store the address. Read the whole file and fill the map. Then, when you search the name you will use std::map::find that will do a binary search. At the end of the program you iterate through the map and write it to the file. If you have multiple entries with the same name you may consider multimap. Since you post it to the Manage C++ you may also consider hash_map. Best regards, Alexandru Savescu
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Hi everyone, I need advice regardin my problem, here's my problem: I have a Text File(serves as my database) with 3 colums fixed length, example Name Address Age AAA 123 Anywhere 12 BBB .... ... Joseph 345 Somewhere 15 Rosie 098 Cool DC 20 I need to search this Text File, in the real world this Text File migh contain 1 Million records as soon as we populate our database. My question is... what is the fastest way to search for a particular string in this text file. Note: I only search for the name, If I find the name... I need to get the enrite line and process it. I will really appreciate any help that you can give me. Thanks/Regards Sidney
Hi everyone, i tried to use the multimap(STL) but I got an error "fatal error: Cannot open include file: 'multimap' C++" I alread installed the all the files that I got from sgi... STL Version 3.3, I installed it in "C:\Program Files\Microsoft Visual Studio\VC98\Include" What could be the problem? Thanks/Regards Sidney
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You can look at the article on CP about STL here. Also you can read MSDN (the one that comes with .NET is nicer than the VC6.0's one), or the SGI documentation. Best regards, Alexandru Savescu
Hi Alexandru, I get an error in my code when I try to use the multimap, the error is "Cannot open include file: 'multimap' C++" can you help me? here's my code: #include #include #include using namespace std; struct ltstr { bool operator()(const char* s1, const char* s2) const { return strcmp(s1, s2) < 0; } }; int main() { multimap m; m.insert(pair("a", 1)); m.insert(pair("c", 2)); m.insert(pair("b", 3)); m.insert(pair("b", 4)); m.insert(pair("a", 5)); m.insert(pair("b", 6)); cout << "Number of elements with key a: " << m.count("a") << endl; cout << "Number of elements with key b: " << m.count("b") << endl; cout << "Number of elements with key c: " << m.count("c") << endl; cout << "Elements in m: " << endl; for (multimap::iterator it = m.begin(); it != m.end(); ++it) cout << " [" << (*it).first << ", " << (*it).second << "]" << endl; } Thanks/Regards Sidney
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Hi Alexandru, I get an error in my code when I try to use the multimap, the error is "Cannot open include file: 'multimap' C++" can you help me? here's my code: #include #include #include using namespace std; struct ltstr { bool operator()(const char* s1, const char* s2) const { return strcmp(s1, s2) < 0; } }; int main() { multimap m; m.insert(pair("a", 1)); m.insert(pair("c", 2)); m.insert(pair("b", 3)); m.insert(pair("b", 4)); m.insert(pair("a", 5)); m.insert(pair("b", 6)); cout << "Number of elements with key a: " << m.count("a") << endl; cout << "Number of elements with key b: " << m.count("b") << endl; cout << "Number of elements with key c: " << m.count("c") << endl; cout << "Elements in m: " << endl; for (multimap::iterator it = m.begin(); it != m.end(); ++it) cout << " [" << (*it).first << ", " << (*it).second << "]" << endl; } Thanks/Regards Sidney
Hello sidney The < and > tags were stripped by the html parser. Please send the code between <pre> and </pre> so I can see what you include and what include not. However this code sould work
#include <multimap>
using namespace std;
....Best regards, Alexandru Savescu
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Hello sidney The < and > tags were stripped by the html parser. Please send the code between <pre> and </pre> so I can see what you include and what include not. However this code sould work
#include <multimap>
using namespace std;
....Best regards, Alexandru Savescu
Here's the code: #include #include #include using namespace std; struct ltstr { bool operator()(const char* s1, const char* s2) const { return strcmp(s1, s2) < 0; } }; int main() { multimap m; m.insert(pair("a", 1)); m.insert(pair("c", 2)); m.insert(pair("b", 3)); m.insert(pair("b", 4)); m.insert(pair("a", 5)); m.insert(pair("b", 6)); cout << "Number of elements with key a: " << m.count("a") << endl; cout << "Number of elements with key b: " << m.count("b") << endl; cout << "Number of elements with key c: " << m.count("c") << endl; cout << "Elements in m: " << endl; for (multimap::iterator it = m.begin(); it != m.end(); ++it) cout << " [" << (*it).first << ", " << (*it).second << "]" << endl; } Thanks/Regards Sidney
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Here's the code: #include #include #include using namespace std; struct ltstr { bool operator()(const char* s1, const char* s2) const { return strcmp(s1, s2) < 0; } }; int main() { multimap m; m.insert(pair("a", 1)); m.insert(pair("c", 2)); m.insert(pair("b", 3)); m.insert(pair("b", 4)); m.insert(pair("a", 5)); m.insert(pair("b", 6)); cout << "Number of elements with key a: " << m.count("a") << endl; cout << "Number of elements with key b: " << m.count("b") << endl; cout << "Number of elements with key c: " << m.count("c") << endl; cout << "Elements in m: " << endl; for (multimap::iterator it = m.begin(); it != m.end(); ++it) cout << " [" << (*it).first << ", " << (*it).second << "]" << endl; } Thanks/Regards Sidney
Well, the multimap header does not exists. Include and it will work; #include using namespace std; etc. Best regards, Alexandru Savescu
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Hi everyone, i tried to use the multimap(STL) but I got an error "fatal error: Cannot open include file: 'multimap' C++" I alread installed the all the files that I got from sgi... STL Version 3.3, I installed it in "C:\Program Files\Microsoft Visual Studio\VC98\Include" What could be the problem? Thanks/Regards Sidney
I think you need not replace the STL that comes with Visual C with the SGI implementation. Best regards, Alexandru Savescu