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//Download by http://www.NewXing.com /* * This file contains code from "C++ Primer, Fourth Edition", by Stanley B. * Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the * copyright and warranty notices given in that book: * * "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo." * * * "The authors and publisher have taken care in the preparation of this book, * but make no expressed or implied warranty of any kind and assume no * responsibility for errors or omissions. No liability is assumed for * incidental or consequential damages in connection with or arising out of the * use of the information or programs contained herein." * * Permission is granted for this code to be used for educational purposes in * association with the book, given proper citation if and when posted or * reproduced.Any commercial use of this code requires the explicit written * permission of the publisher, Addison-Wesley Professional, a division of * Pearson Education, Inc. Send your request for permission, stating clearly * what code you would like to use, and in what specific way, to the following * address: * * Pearson Education, Inc. * Rights and Contracts Department * 75 Arlington Street, Suite 300 * Boston, MA 02216 * Fax: (617) 848-7047 */ #include <string> using std::string; #include <iostream> using std::cout; using std::endl; #include <cstring> int main() { const char *cp1 = "A string example"; const char *cp2 = "A different string"; int i = strcmp(cp1, cp2); // i is positive i = strcmp(cp2, cp1); // i is negative i = strcmp(cp1, cp1); // i is zero cout << strlen(cp1) << endl; // prints 16; strlen ignores the null if (cp1 < cp2) // compares addresses, not the values pointed to ; char ca[] = {'C', '+', '+'}; // not null-terminated cout << strlen(ca) << endl; // disaster: ca isn't null-terminated // behavior of this print statement is undefined // Dangerous: What happens if we miscalculate the size of largeStr? char largeStr[16 + 18 + 2]; // will hold cp1 a space and cp2 strcpy(largeStr, cp1); // copies cp1 into largeStr strcat(largeStr, " "); // adds a space at end of largeStr strcat(largeStr, cp2); // concatenates cp2 to largeStr // prints A string example A different string cout << largeStr << endl; // Somewhat safer: use the ``strn'' versions to copy and concatenate { char largeStr[16 + 18 + 2]; // to hold cp1 a space and cp2 strncpy(largeStr, cp1, 17); // size to copy includes the null strncat(largeStr, " ", 2); // pedantic, but a good habit strncat(largeStr, cp2, 19); // adds at most 18 characters, plus a null cout << largeStr << endl; } // Best approach: use strings not char arrays! { string largeStr = cp1; // initialize largeStr as a copy of cp1 largeStr += " "; // add space at end of largeStr largeStr += cp2; // concatenate cp2 onto end of largeStr cout << largeStr << endl; } return 0; }