comparison: docs/src/modules.md
docs/src/modules.md
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| 106 More features for convenient use of the buffer can be enabled, like automatic | 106 More features for convenient use of the buffer can be enabled, like automatic |
| 107 memory management and automatic resizing of the buffer space. | 107 memory management and automatic resizing of the buffer space. |
| 108 See the documentation of the macro constants in the header file for more | 108 See the documentation of the macro constants in the header file for more |
| 109 information. | 109 information. |
| 110 | 110 |
| 111 ### Add line numbers to a file | |
| 112 | |
| 113 When reading a file line by line, you have three options: first, you could limit | |
| 114 the maximum supported line length. | |
| 115 Second, you allocate a god buffer large | |
| 116 enough for the most lines a text file could have. | |
| 117 And third, undoubtedly the best option, you start with a small buffer, which | |
| 118 adjusts on demand. | |
| 119 An `UcxBuffer` can be created to do just that for you. | |
| 120 Just pass the `UCX_BUFFER_AUTOEXTEND` option to the initialization function. | |
| 121 Here is a full working program, which adds line numbers to a file. | |
| 122 ```C | |
| 123 #include <stdio.h> | |
| 124 #include <ucx/buffer.h> | |
| 125 #include <ucx/utils.h> | |
| 126 | |
| 127 int main(int argc, char** argv) { | |
| 128 | |
| 129 if (argc != 2) { | |
| 130 fprintf(stderr, "Usage: %s <file>\n", argv[0]); | |
| 131 return 1; | |
| 132 } | |
| 133 | |
| 134 FILE* input = fopen(argv[1], "r"); | |
| 135 if (!input) { | |
| 136 perror("Canno read input"); | |
| 137 return 1; | |
| 138 } | |
| 139 | |
| 140 const size_t chunksize = 256; | |
| 141 | |
| 142 UcxBuffer* linebuf = | |
| 143 ucx_buffer_new( | |
| 144 NULL, // the buffer should manage the memory area for us | |
| 145 chunksize, // initial buffer size should be the chunk size | |
| 146 UCX_BUFFER_AUTOEXTEND); // the buffer will grow when necessary | |
| 147 | |
| 148 size_t lineno = 1; | |
| 149 do { | |
| 150 // read line chunk | |
| 151 size_t read = ucx_stream_ncopy( | |
| 152 input, linebuf, fread, ucx_buffer_write, chunksize); | |
| 153 if (read == 0) break; | |
| 154 | |
| 155 // handle line endings | |
| 156 do { | |
| 157 sstr_t bufstr = ucx_buffer_to_sstr(linebuf); | |
| 158 sstr_t nl = sstrchr(bufstr, '\n'); | |
| 159 if (nl.length == 0) break; | |
| 160 | |
| 161 size_t linelen = bufstr.length - nl.length; | |
| 162 sstr_t linestr = sstrsubsl(bufstr, 0, linelen); | |
| 163 | |
| 164 printf("%zu: %" PRIsstr "\n", lineno++, SFMT(linestr)); | |
| 165 | |
| 166 // shift the buffer to the next line | |
| 167 ucx_buffer_shift_left(linebuf, linelen+1); | |
| 168 } while(1); | |
| 169 | |
| 170 } while(1); | |
| 171 | |
| 172 // print the 'noeol' line, if any | |
| 173 sstr_t lastline = ucx_buffer_to_sstr(linebuf); | |
| 174 if (lastline.length > 0) { | |
| 175 printf("%zu: %" PRIsstr, lineno, SFMT(lastline)); | |
| 176 } | |
| 177 | |
| 178 fclose(input); | |
| 179 ucx_buffer_free(linebuf); | |
| 180 | |
| 181 return 0; | |
| 182 } | |
| 183 ``` | |
| 184 | |
| 111 ## List | 185 ## List |
| 112 | 186 |
| 113 *Header file:* [list.h](api/list_8h.html) | 187 *Header file:* [list.h](api/list_8h.html) |
| 114 *Required modules:* [Allocator](#allocator) | 188 *Required modules:* [Allocator](#allocator) |
| 115 | 189 |
