#include <stdio.h> #include <string.h> /* * This is a plain C version of the C++ string example. It contains several * things which I may not explain fully, and is mostly to show that using * strings in plain C is ... special. * * Plain C strings are fixed length, and this program sets a limit of 100, * so the semantics will differ from the C++ one if you enter long string. */ int main() { // This declares line as an array of 100 chars, which can // store a string of size 0 to 99. The extra byte is needed // for a terminator, which is a zero byte. Fgets reads a line // much as getline, but if the line has more than characters // than line can hold, it just stops reading, leaving the // remaining characters. Also, it leaves the \n in the // string, which I have to get rid of. Stdin is the plain C // equivalent of cin, but in most cases itis also the default // for reading. char line[100]; printf("Please enter a line:\n> "); fgets(line, sizeof line, stdin); line[strlen(line)-1] = 0; // This removes the last character. // Again, read a word, this time using scanf. Scanf %s is similar // to reading a string with cout >>, in that it skips leading // spaces and reads a non-blank string. Unlike all other types, // arrays do not need an & on the variable. char word[100]; printf("Please enter a single word: "); scanf("%s", word); // Printf uses %s for a string. printf("You entered %s and %s\n", word, line); // Plain C strings can be compared with the strcmp() utility, which // returns negative, zero, or positive much like Java .compareTo(). if(strcmp(word,"wombat") == 0) printf("You entered \"wombat\". My favorite word!\n"); // The find operation searches for one string in another, and returns // the position, or NULL to indicate not found. The position is a // pointer, which is a pointer, the memory address of the found string. char *loc = strstr(line, word); if(loc == NULL) printf("Your word is not in your line. Oh well.\n"); else printf("Your word is at %d in your line.\n", loc - line); // Plain C strings are arrays of characters, terminated by character 0. for(int i = 0; word[i] != 0; ++i) { printf("-%c- ", word[i]); } printf("\n"); }