73 lines
2.8 KiB
C++
73 lines
2.8 KiB
C++
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//
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// Chpater 03 program 6: Ch_03_06.cpp
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#include <iostream>
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#include <iomanip> // for using setw and setprecision
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#include <string> // so that the string class can be used
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using namespace std;
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main()
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{
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string str1 = "This is a programming class";
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string str2 = ""; // str2 contains the substring,
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// output what is contained in string1, with a position indicator
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cout << endl;
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cout << "Substrings will be found in the following string:\n";
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cout << " 0123456789012345678901234567890\n";
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cout << "str1: " << str1 << endl << endl;
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// Look at various substring values
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// the substrings are output between the arrow indicators
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// of ==> and <==
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// Length of 0 attempt - null string
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str2 = str1.substr(4,0);
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cout << "str1.substr(4,0) should return null string\n";
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cout << "str2 contains the null ==>" << str2 << "<== string\n";
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// two valid attempts - one with literals, one using find function
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str2 = str1.substr(6,5);
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cout << "\nstr1 substring (6,5) is ==>" << str2 << "<==" << endl;
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cout << endl << "substring of str1 starting with 'pro'\n" << "and containing 8 characters\n";
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str2 = str1.substr(str1.find("pro"),8);
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cout << "str1 substring (str1.find(\"pro\"),8) is ==>" << str2 <<"<==" << endl;
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// substring going past end of string
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cout << "\nExtracting beyond the end of the string is okay\n";
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str2 = str1.substr(20,20);
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cout << "str1 substring(20,20) is ==>" << str2 << "<==" << endl;
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// substring starting at position 1
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str2 = str1.substr(1,5);
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cout << "\nstr1 substring(1,5) is ==>" << str2 << "<==" << endl << endl;
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cout.flush(); // make sure the above is printed
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//cout << "Substring with a negative starting position: " << endl;
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// this results in a runtime error with out of range substring error
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//str2 = str1.substr(-40,3);
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//cout << "str2:" << str2 << "<==\n";
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// here length is -3, -3 will be converted to a large
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// positive number due to the way unsigned integers are
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// stored in the computer. therefore , the rest of the
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// string from the starting position will be pulled out
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// as the substring
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str2 = str1.substr(4,-3);
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cout << "Substring starting at position 4 with length -3\n";
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cout << "str2:" << str2 << "<==\n\n";
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cout << "-3 assinged to unsigned integer data types becomes\n";
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cout << "a large positive number\n";
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cout << "-3 assigned to unsigned int: " << unsigned(-3) << endl;
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cout << "-3 assigned to unsigned long: " << (unsigned long)(-3) << endl << endl;
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cout << "\nThe following causes an abort due to starting position\n";
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cout << "Attempting str1 substring (40,3):\n";
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str2 = str1.substr(40,3);
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cout << str2;
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// starting beyond the end of the string
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return 0;
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}
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