从文件中读取行而不是 return 全部

Question

我试图将文件中的单词保存到数组中，但我只读取了前 8 个。

下面是我的代码。

#define BUF 128 /* can change the buffer size as well */


char ** readFileContentArray(char* filename){

   int lines = 128;
   char **     strLines = (char **)malloc(sizeof(char*)*lines);
   FILE *plist = NULL;
   int i = 0;

   char line[4];

   plist = fopen(filename, "r");
   while(fgets(line, BUF, plist)) {

       if(i >= lines){
           strLines = (char **)realloc(strLines, (lines*2) * sizeof(char *));
           lines = lines*2;
       }

       strLines[i] = strdup(line);
       i++;
   }


   return strLines;
}

我正在读取的文件格式如下：

aaaa

bbbb

cccc

dddd

eeee

ffff

gggg

hhhh

iiii

jjjj

Answer 1

您的代码有几个问题。

Don't cast the result of malloc/calloc/realloc in C
您不检查 fopen 是否成功。这可以通过检查其 return 值来完成。 fopen returns NULL 失败。
您允许fgets将128个字符写入line，最多可容纳4个字符。

固定码：

#define BUF 128 /* Change to max size of a line */


char ** readFileContentArray(char* filename){

   int lines = 128;
   char **     strLines = malloc(sizeof(char*) * lines);

   if(strLines == NULL) //If malloc failed
       return NULL; 
   FILE *plist = NULL;
   int i = 0;

   char line[BUF]; //Allocate BUF size

   if((plist = fopen(filename, "r")) == NULL) //If fopen failed
       return NULL; 
   while(fgets(line, BUF, plist)) { 

       if(i >= lines){
           char* temp;
           if((temp = realloc(strLines, (lines*2) * sizeof(char *))) == NULL) //If realloc failed
           {
               free(strLines);
               return NULL;
           ]
           lines = lines*2;
       }

       strLines[i] = strdup(line);
       i++;
   }

   fclose(plist); //Close file after its use

   return realloc(strLines, i * sizeof(char*)); //Return correct size
}

Answer 2

您可以将指针传递给两个整数，以便调用者可以知道数组中分配了多少项。
调用 char **strArray = readFileContentArray ( "file.txt", &total, &used);
结果可能会打印

for ( i = 0; i < used; i++) {
    printf ( "%s", strArray[i]);
}

同样免费。

for ( i = 0; i < used; i++) {
    free ( strArray[i]);
}
free ( strArry);

这些将在调用函数中使用。

char ** readFileContentArray(char* filename, int *lines, int *used){

    *lines = 128;
    *used = 0;
    char **strLines = malloc(sizeof(char*)*(*lines));
    char **strTemp = NULL;
    FILE *plist = NULL;

    char line[6];

    plist = fopen(filename, "r");
    if ( plist == NULL) {
        return NULL;
    }
    while(fgets(line, sizeof ( line), plist)) {
        if ( line[0] == '\n') {
            continue;//blank line
        }
        if(*used >= *lines){
            strTemp = realloc(strLines, ((*lines)*2) * sizeof(char *));
            if ( strTemp == NULL) {
                printf ( "realloc failed\n");
                return strLines;
            }
            strLines = strTemp;
            *lines = (*lines)*2;
        }
        strLines[*used] = strdup(line);
        *used += 1;
    }
    return strLines;
}

从文件中读取行而不是 return 全部

Read lines from file not return all

c

fopen

readfile

fgets