| 1 | /* Scramble the "inner" letters of each word in the input into a random order, and output the result. Non-word (that is, non-alphabetical) characters, and the first and last letters of each word, are left alone. |
| 2 | * Output to something other than stdout will append to the file instead of overwriting it - this may be undesirable, and can be changed if so. |
| 3 | */ |
| 4 | |
| 5 | /* Copyright 2009-07-11 Andrew J. Buehler. |
| 6 | */ |
| 7 | |
| 8 | /* This program is free software: you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License as published by |
| 10 | * the Free Software Foundation, either version 3 of the License, or |
| 11 | * (at your option) any later version. |
| 12 | * This program is distributed in the hope that it will be useful, |
| 13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 15 | * GNU General Public License for more details. |
| 16 | * You should have received a copy of the GNU General Public License |
| 17 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| 18 | */ |
| 19 | |
| 20 | #include <stdio.h> |
| 21 | #include <ctype.h> // for isalpha() |
| 22 | #include <stdlib.h> // for malloc()/calloc()/realloc()/free() and rand()/srand() |
| 23 | #include <string.h> // for strlen() |
| 24 | #include <time.h> // for time() |
| 25 | |
| 26 | #define ALLOW_FILE_IO 0 |
| 27 | |
| 28 | |
| 29 | /* strips 'reduction' characters from the end of the input string and returns the result |
| 30 | * works only if strlen(string> >= reduction, which is the case in the only place it is presently called |
| 31 | */ |
| 32 | char *shorten_string(char *string, int reduction) { |
| 33 | int i; |
| 34 | |
| 35 | i = strlen(string); |
| 36 | |
| 37 | for (; reduction > 0; reduction--, i--) { |
| 38 | string[i-1] = '\0'; // would it work to use an 'i-reduction' approach instead, similar to what was later done in narrow_string()? |
| 39 | } |
| 40 | |
| 41 | return string; |
| 42 | } |
| 43 | |
| 44 | /* strips 'reduction' characters from the beginning and the end of the input string and returns the result |
| 45 | * works only if(strlen(string) >= 2*reduction), which is the case in the only place it is presently called |
| 46 | */ |
| 47 | char *narrow_string(char *string, int reduction) { |
| 48 | int i = reduction; |
| 49 | |
| 50 | while(string[i]) { |
| 51 | string[i-reduction] = string[i]; |
| 52 | i++; |
| 53 | } |
| 54 | string[i-reduction] = '\0'; |
| 55 | |
| 56 | return shorten_string(string, reduction); |
| 57 | } |
| 58 | |
| 59 | int all_one_letter(char *string) { |
| 60 | char c; |
| 61 | int i; |
| 62 | |
| 63 | c = string[0]; |
| 64 | for(i = 1; string[i] != '\0'; i++) { |
| 65 | if(c != string[i]) { |
| 66 | return 0; // a nonduplicate letter has been found |
| 67 | } |
| 68 | c = string[i]; |
| 69 | } |
| 70 | |
| 71 | return 1; // reached the end of the string having found only duplicate letters, so it's all one letter |
| 72 | } |
| 73 | |
| 74 | /* randomly reorders the contents of the string |
| 75 | * WARNING: frees the input string and returns a replacement |
| 76 | */ |
| 77 | char *scramble_string(char *string) { |
| 78 | char *ret, *tmpstr; |
| 79 | int len, i, j; |
| 80 | |
| 81 | len = strlen(string); |
| 82 | if(len < 2) return string; // can't scramble a 1-character string or an empty string! |
| 83 | if(all_one_letter(string)) return(string); // can't scramble a string which consists entirely of one letter! |
| 84 | |
| 85 | ret = strdup(string); |
| 86 | |
| 87 | while(strcmp(string, ret) == 0) { |
| 88 | j = 0; |
| 89 | tmpstr = strdup(string); |
| 90 | while(len > 0) { |
| 91 | i = rand() % len; |
| 92 | ret[j] = tmpstr[i]; |
| 93 | j++; |
| 94 | while(tmpstr[i] != '\0') { |
| 95 | tmpstr[i] = tmpstr[i+1]; |
| 96 | i++; |
| 97 | } |
| 98 | len--; |
| 99 | } |
| 100 | free(tmpstr); |
| 101 | len = strlen(string); |
| 102 | } |
| 103 | |
| 104 | |
| 105 | free(string); |
| 106 | return ret; |
| 107 | } |
| 108 | |
| 109 | char *clear_string(char *string) { |
| 110 | int i; |
| 111 | |
| 112 | i = strlen(string); |
| 113 | |
| 114 | for(; i >= 0 ; i--) { |
| 115 | string[i] = '\0'; |
| 116 | } |
| 117 | |
| 118 | return string; |
| 119 | } |
| 120 | |
| 121 | int main(int argc, char **argv) { |
| 122 | int word_length; |
| 123 | char c, tempchar, *word, *rword; |
| 124 | FILE *infile, *outfile; |
| 125 | |
| 126 | #if ALLOW_FILE_IO |
| 127 | /* open files, if any other than stdin and stdout */ |
| 128 | if(argc > 1) { |
| 129 | if(!strcmp(argv[1], "--help") || |
| 130 | !strcmp(argv[1], "-h")) { |
| 131 | printf("Usage: %s [INPUT_FILENAME] [OUTPUT_FILENAME]\n", argv[0]); |
| 132 | printf("If INPUT_FILENAME is omitted or is '-', read from standard input\nIf OUTPUT_FILENAME is omitted or is '-', print to standard output\n"); |
| 133 | return 0; |
| 134 | } |
| 135 | |
| 136 | if(strcmp(argv[1], "-")) { |
| 137 | infile = fopen(argv[1], "r"); |
| 138 | if(infile == NULL) { |
| 139 | fprintf(stderr, "Unable to open input file %s for reading\n", argv[1]); |
| 140 | return 1; |
| 141 | } |
| 142 | } else { |
| 143 | infile = stdin; |
| 144 | } |
| 145 | |
| 146 | if(argc > 2) { |
| 147 | if(strcmp(argv[2], "-")) { |
| 148 | outfile = fopen(argv[2], "a"); |
| 149 | if(outfile == NULL) { |
| 150 | fprintf(stderr, "Unable to open output file %s for writing\n", argv[2]); |
| 151 | return 2; |
| 152 | } |
| 153 | } else { |
| 154 | outfile = stdout; |
| 155 | } |
| 156 | } |
| 157 | } else { // no arguments specified |
| 158 | infile = stdin; |
| 159 | outfile = stdout; |
| 160 | } |
| 161 | #else |
| 162 | infile = stdin; |
| 163 | outfile = stdout; |
| 164 | #endif |
| 165 | |
| 166 | srand(time(NULL)); // needed for scramble_string() to actually be random |
| 167 | |
| 168 | word_length = 0; |
| 169 | word = malloc(sizeof(char)); |
| 170 | word[0] = '\0'; |
| 171 | c = fgetc(infile); |
| 172 | |
| 173 | if(feof(infile)) { |
| 174 | printf("Reached EOF while reading the first character of the input file!\n"); |
| 175 | free(word); |
| 176 | return 4; |
| 177 | } |
| 178 | |
| 179 | while(!feof(infile)) { |
| 180 | if(isalpha(c)) { |
| 181 | rword = realloc(word, word_length+2); // one for the new character, one for the null |
| 182 | if(rword == NULL){ |
| 183 | free(word); |
| 184 | fprintf(stderr, "Unable to allocate memory\n"); |
| 185 | return 5; |
| 186 | } |
| 187 | word = rword; |
| 188 | word[word_length] = c; |
| 189 | word[word_length + 1] = '\0'; // duplicate addition with the next line, but possibly more readable |
| 190 | word_length++; |
| 191 | } else { |
| 192 | if(word_length) { |
| 193 | word_length--; |
| 194 | fputc(word[0], outfile); |
| 195 | if(word_length) { |
| 196 | tempchar = word[word_length]; |
| 197 | word = scramble_string(narrow_string(word, 1)); |
| 198 | fprintf(outfile, "%s", word); |
| 199 | fputc(tempchar, outfile); |
| 200 | } |
| 201 | word = clear_string(word); |
| 202 | word_length = 0; |
| 203 | } |
| 204 | fputc(c, outfile); |
| 205 | } |
| 206 | fflush(outfile); |
| 207 | c = fgetc(infile); |
| 208 | } |
| 209 | |
| 210 | free(word); |
| 211 | return 0; |
| 212 | } |