函数设计原则：
函数应该是无状态的，就是第一次调用和第二次调用是一样的。
getchar返回值是int型。
优秀代码欣赏：Eclipse代码
1 /******************************************************************************* 2 * Copyright (c) 2000, 2005 IBM Corporation and others. 3 * All rights reserved. This program and the accompanying materials 4 * are made available under the terms of the Eclipse Public License v1.0 5 * which accompanies this distribution, and is available at 6 * http://www.eclipse.org/legal/epl-v10.html 7 * 8 * Contributors: 9 * IBM Corporation - initial API and implementation 10 * Kevin Cornell (Rational Software Corporation) 11 *******************************************************************************/ 12 13 /* Eclipse Launcher Utility Methods */ 14 15 #include "eclipseOS.h" 16 #include "eclipseCommon.h" 17 #include "eclipseUtil.h" 18 19 #include <string.h> 20 #include <stdlib.h> 21 #include <stdio.h> 22 #include <sys/stat.h> 23 #ifdef _WIN32 24 #include <direct.h> 25 #else 26 #include <unistd.h> 27 #include <strings.h> 28 #endif 29 30 #define MAX_LINE_LENGTH 256 31 32 /* Is the given VM J9 */ 33 int isJ9VM( _TCHAR* vm ) 34 { 35 _TCHAR * ch = NULL, *ch2 = NULL; 36 int res = 0; 37 38 if (vm == NULL) 39 return 0; 40 41 ch = lastDirSeparator( vm ); 42 if (isVMLibrary(vm)) { 43 /* a library, call it j9 if the parent dir is j9vm */ 44 if(ch == NULL) 45 return 0; 46 ch[0] = 0; 47 ch2 = lastDirSeparator(vm); 48 if(ch2 != NULL) { 49 res = (_tcsicmp(ch2 + 1, _T_ECLIPSE("j9vm")) == 0); 50 } 51 ch[0] = dirSeparator; 52 return res; 53 } else { 54 if (ch == NULL) 55 ch = vm; 56 else 57 ch++; 58 return (_tcsicmp( ch, _T_ECLIPSE("j9") ) == 0); 59 } 60 } 61 62 int checkProvidedVMType( _TCHAR* vm ) 63 { 64 _TCHAR* ch = NULL; 65 struct _stat stats; 66 67 if (vm == NULL) return VM_NOTHING; 68 69 if (_tstat(vm, &stats) == 0 && (stats.st_mode & S_IFDIR) != 0) { 70 /* directory */ 71 return VM_DIRECTORY; 72 } 73 74 ch = _tcsrchr( vm, _T_ECLIPSE('.') ); 75 if(ch == NULL) 76 return VM_OTHER; 77 78 #ifdef _WIN32 79 if (_tcsicmp(ch, _T_ECLIPSE(".dll")) == 0) 80 #else 81 if ((_tcsicmp(ch, _T_ECLIPSE(".so")) == 0) || (_tcsicmp(ch, _T_ECLIPSE(".jnilib")) == 0) || (_tcsicmp(ch, _T_ECLIPSE(".dylib")) == 0)) 82 #endif 83 { 84 return VM_LIBRARY; 85 } 86 87 if (_tcsicmp(ch, _T_ECLIPSE(".ee")) == 0) 88 return VM_EE_PROPS; 89 90 return VM_OTHER; 91 } 92 93 /* 94 * pathList is a pathSeparator separated list of paths, run each through 95 * checkPath and recombine the results. 96 * New memory is always allocated for the result 97 */ 98 _TCHAR * checkPathList( _TCHAR* pathList, _TCHAR* programDir, int reverseOrder) { 99 _TCHAR * c1, *c2; 100 _TCHAR * checked, *result; 101 size_t checkedLength = 0, resultLength = 0; 102 size_t bufferLength = _tcslen(pathList); 103 104 result = malloc(bufferLength * sizeof(_TCHAR)); 105 c1 = pathList; 106 while (c1 != NULL && *c1 != _T_ECLIPSE('\0')) 107 { 108 c2 = _tcschr(c1, pathSeparator); 109 if (c2 != NULL) 110 *c2 = 0; 111 112 checked = checkPath(c1, programDir, reverseOrder); 113 checkedLength = _tcslen(checked); 114 if (resultLength + checkedLength + 1> bufferLength) { 115 bufferLength += checkedLength + 1; 116 result = realloc(result, bufferLength * sizeof(_TCHAR)); 117 } 118 119 if(resultLength > 0) { 120 result[resultLength++] = pathSeparator; 121 result[resultLength] = _T_ECLIPSE('\0'); 122 } 123 _tcscpy(result + resultLength, checked); 124 resultLength += checkedLength; 125 126 if(checked != c1) 127 free(checked); 128 if(c2 != NULL) 129 *(c2++) = pathSeparator; 130 c1 = c2; 131 } 132 133 return result; 134 } 135 136 _TCHAR * concatStrings(_TCHAR**strs) { 137 return concatPaths(strs, 0); 138 } 139 140 _TCHAR * concatPaths(_TCHAR** strs, _TCHAR separator) { 141 _TCHAR separatorString[] = { separator, 0 }; 142 _TCHAR * result; 143 int i = -1; 144 size_t length = 0; 145 /* first count how large a buffer we need */ 146 while (strs[++i] != NULL) { 147 length += _tcslen(strs[i]) + (separator != 0 ? 1 : 0); 148 } 149 150 result = malloc((length + 1) * sizeof(_TCHAR)); 151 result[0] = 0; 152 i = -1; 153 while (strs[++i] != NULL) { 154 result = _tcscat(result, strs[i]); 155 if (separator != 0) 156 result = _tcscat(result, separatorString); 157 } 158 return result; 159 } 160 161 /* 162 * buffer contains a pathSeparator separated list of paths, check 163 * that it contains all the paths given. Each path is expected to be 164 * terminated with a pathSeparator character. 165 */ 166 int containsPaths(_TCHAR * str, _TCHAR** paths) { 167 _TCHAR * buffer; 168 _TCHAR * c; 169 int i; 170 171 /* terminate the string with a pathSeparator */ 172 buffer = malloc((_tcslen(str) + 2) * sizeof(_TCHAR)); 173 _stprintf(buffer, _T_ECLIPSE("%s%c"), str, pathSeparator); 174 175 for (i = 0; paths[i] != NULL; i++) { 176 c = _tcsstr(buffer, paths[i]); 177 if ( c == NULL || !(c == buffer || *(c - 1) == pathSeparator)) 178 { 179 /* entry not found */ 180 free(buffer); 181 return 0; 182 } 183 } 184 free(buffer); 185 return 1; 186 } 187 188 int isVMLibrary( _TCHAR* vm ) 189 { 190 _TCHAR *ch = NULL; 191 if (vm == NULL) return 0; 192 ch = _tcsrchr( vm, '.' ); 193 if(ch == NULL) 194 return 0; 195 #ifdef _WIN32 196 return (_tcsicmp(ch, _T_ECLIPSE(".dll")) == 0); 197 #else 198 return (_tcsicmp(ch, _T_ECLIPSE(".so")) == 0) || (_tcsicmp(ch, _T_ECLIPSE(".jnilib")) == 0) || (_tcsicmp(ch, _T_ECLIPSE(".dylib")) == 0); 199 #endif 200 } 201 202 #ifdef AIX 203 204 #include <sys/types.h> 205 #include <time.h> 206 207 /* Return the JVM version in the format x.x.x 208 */ 209 char* getVMVersion( char *vmPath ) 210 { 211 char cmd[MAX_LINE_LENGTH]; 212 char lineString[MAX_LINE_LENGTH]; 213 char* firstChar; 214 char fileName[MAX_LINE_LENGTH]; 215 time_t curTime; 216 FILE* fp; 217 int numChars = 0; 218 char* version = NULL; 219 220 /* Define a unique filename for the java output. */ 221 (void) time(&curTime); 222 (void) sprintf(fileName, "/tmp/tmp%ld.txt", curTime); 223 224 /* Write java -version output to a temp file */ 225 (void) sprintf(cmd,"%s -version 2> %s", vmPath, fileName); 226 (void) system(cmd); 227 228 fp = fopen(fileName, "r"); 229 if (fp != NULL) 230 { 231 /* Read java -version output from a temp file */ 232 if (fgets(lineString, MAX_LINE_LENGTH, fp) == NULL) 233 lineString[0] = '\0'; 234 fclose(fp); 235 unlink(fileName); 236 237 /* Extract version number */ 238 firstChar = (char *) (strchr(lineString, '"') + 1); 239 if (firstChar != NULL) 240 numChars = (int) (strrchr(lineString, '"') - firstChar); 241 242 /* Allocate a buffer and copy the version string into it. */ 243 if (numChars > 0) 244 { 245 version = malloc( numChars + 1 ); 246 strncpy(version, firstChar, numChars); 247 version[numChars] = '\0'; 248 } 249 } 250 251 return version; 252 } 253 254 /* Compare JVM Versions of the form "x.x.x..." 255 * 256 * Returns -1 if ver1 < ver2 257 * Returns 0 if ver1 = ver2 258 * Returns 1 if ver1 > ver2 259 */ 260 int versionCmp(char *ver1, char *ver2) 261 { 262 char* dot1; 263 char* dot2; 264 int num1; 265 int num2; 266 267 dot1 = strchr(ver1, '.'); 268 dot2 = strchr(ver2, '.'); 269 270 num1 = atoi(ver1); 271 num2 = atoi(ver2); 272 273 if (num1 > num2) 274 return 1; 275 276 if (num1 < num2) 277 return -1; 278 279 if (dot1 && !dot2) /* x.y > x */ 280 return 1; 281 282 if (!dot1 && dot2) /* x < x.y */ 283 return -1; 284 285 if (!dot1 && !dot2) /* x == x */ 286 return 0; 287 288 return versionCmp((char*)(dot1 + 1), (char*)(dot2 + 1) ); 289 } 290 #endif /* AIX */
小结：
