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45 lines
1.5 KiB
C++
45 lines
1.5 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2011, 2012.
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This file is part of the Sortix C Library.
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The Sortix C Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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The Sortix C Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
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string/strstr.cpp
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Locate a substring.
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*******************************************************************************/
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#include <string.h>
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// TODO: This simple and hacky implementation runs in O(N^2) even though this
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// problem can be solved in O(N).
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extern "C" char* strstr(const char* haystack, const char* needle)
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{
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if ( !needle[0] )
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return (char*) haystack;
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for ( size_t i = 0; haystack[i]; i++ )
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{
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bool diff = false;
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for ( size_t j = 0; needle[j]; j++ )
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{
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if ( haystack[i+j] != needle[j] ) { diff = true; break; }
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}
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if ( diff )
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continue;
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return (char*) haystack + i;
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}
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return NULL;
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}
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