使用標記方法C Seg錯誤：可能的malloc錯誤？

Question

我真的很難過。當我運行我的程序時，我不斷收到分段錯誤錯誤。我一直在玩弄它一段時間，我懷疑錯誤可能在於我的內存分配或釋放。請幫助:(我不知道我在做什麼錯誤謝謝

CODE：！

163 //Arguments: s1, delimter                   
164 //Returns a pointer to a char array containing entries for each token in s1. Think of this   
165 //as a 2-D array. Each row contains a char* (token). This function creates a NEW char**   
166 //variable and NEW char* variables for each token. Your method should be memory efficient.   
167 //In other words, the space created for each token should be an exact fit for the space    
168 //that token needs. If a token is five characters, allocate 5 bytes (plus null terminator).  
169 //The function also writes the number of tokens into the numTokens variable.  

170 char** tokenize(const char *s, char delimiter, int *numTokens){ 
171 //set variables                     
172 int i,j,a; 
173  //alloacte space                    
174 char **arr = (char **)malloc((*numTokens) * sizeof(char *)); 
175 for (i=0; i<(*numTokens); i++){ 
176  arr[i] = (char *)malloc(50 * sizeof(char)); 
177 } 
178 
179 //while loop to search commence second search              
180 //fill new 2d array                    
181 while(s[a] != '\0'){ 
182  if(s[a] == delimiter){ 
183  j++; 
184  i = 0; 
185  }else{ 
186  arr[i][j] = s[a]; 
187  i++; 
188  } 
189  a++; 
190 }// end while                      
191 
192 //to end arr                      
193 arr[i][j] = '\0'; 
194 
195 return arr; 
196 } 

TEST：

137 char **test; 
138 char *testFour; 
139 int numTokens, *token; 
140 testFour = (char *)calloc(50, sizeof(char)); 
141 sprintf(testFour, "check it with a space"); 
142 token = &numTokens; 
143 
144 test = tokenize(testFour, ' ', token); 
145 
146 if (compare(test[0], "check")) 
147  printf("Test 1: Pass\n"); 
148 else 
149  printf("Test 1: Fail\n"); 
150 if (compare(test[1], "it")) 
151  printf("Test 2: Pass\n"); 
152 else 
153  printf("Test 2: Fail\n"); 
154 if (compare(test[4], "space")) 
155  printf("Test 3: Pass\n"); 
156 else 
157  printf("Test 3: Fail\n"); 

free(testFour); 

Answer 1

您正在使用合格numTokens地址不初始化它，然後使用該地址處的值

char **arr = (char **)malloc((*numTokens) * sizeof(char *)); 

因爲它沒有初始化v alue可能是任何事情，所以應該發生意想不到的事情，例如分段故障。

另外

• Don't cast the result of malloc()
• sizeof(char) == 1通過定義。