C编程 - 从文本文件读取特定的行 [英] C Programming - Read specific line from text file

问题描述

以下是代码：

  int main（）
 {
 struct vinnaren 
 {
 char vinnare [20]; 
 int artal; 
}; 
 struct vinnaren v [10]; 
 int inputrader; 
 int antalrader; //我想让antalrader等于test.txt中的第一行
 //（第一行是5）
 char file_name [256] =test.txt; 
 char buf [512]; 
 FILE * f = fopen（file_name，r）; 
 if（！f）
 {
 exit（0）; 
 
 while（fgets（buf，sizeof buf，f））
 {
 
 printf（％s，buf）; 
} 
 fclose（f）; 
 
 
 
 $ b $ p $这是我的代码。我希望在文件test.txt中添加
 antalrader = line1 
如何从文件中读取特定的行 
 
解决方案
使用此代码，您可以逐行读取文件，并从文本文件中读取特定行： 
 
 
  lineNumber = x; 
 
 static const char filename [] =file.txt; 
 FILE * file = fopen（filename，r）; 
 int count = 0; 
 if（file！= NULL）
 {
 char line [256]; / *或其他合适的最大行大小* / 
 while（fgets（line，sizeof line，file）！= NULL）/ *读一行* / 
 {
 if（count == lineNumber）
 {
 //使用行或函数返回
 //在返回的情况下，首先用fclose（file）关闭文件; 
} 
 else 
 {
 count ++; 
} 
} 
 fclose（file）; 
} 
 else 
 {
 //文件不存在
} 
  
 
Here is the code: 
int main()
{
    struct vinnaren
    {
        char vinnare[20];
        int artal;
    };
    struct vinnaren v[10];
    int inputrader;
    int antalrader;  //I want antalrader to be equal to the first 
                     //line in test.txt(the first line is "5")
    char file_name[256] = "test.txt";
    char buf[512];
    FILE *f = fopen(file_name, "r");
    if (!f)
    {
        exit(0);
    }
    while (fgets(buf, sizeof buf, f))
    {

        printf("%s", buf);
    }
    fclose(f);
}
This is the code I have. I want to make it so that 
antalrader = line1 in the file test.txt
How do I read a specific line from the file?
解决方案
With this code you can read a file line by line and hence read a specific line from the text file:
lineNumber = x;

static const char filename[] = "file.txt";
FILE *file = fopen(filename, "r");
int count = 0;
if ( file != NULL )
{
    char line[256]; /* or other suitable maximum line size */
    while (fgets(line, sizeof line, file) != NULL) /* read a line */
    {
        if (count == lineNumber)
        {
            //use line or in a function return it
            //in case of a return first close the file with "fclose(file);"
        }
        else
        {
            count++;
        }
    }
    fclose(file);
}
else
{
    //file doesn't exist
}


                        
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