在C中用一个编译2个文件命令 [英] Compile 2 file commands in one in C

问题描述

您好我正在研究C中的项目。我想首先打开一个名为op.txt的文件，使用fcanf读取它的第一个数字并将num放入int中。然后我想使用另一个命令将该num写入另一个名为o.txt的文件中



但是如何在main函数中使用第二个File命令使用第一个文件的fopen？



fprint 命令的代码是

  #include   <   stdio.h  >  
  
 main（）
 {
 FILE * fp; 
  int  a =  1 ; 
 fp = fopen（  test.txt，  w +）; 
 fprintf（fp，  int是％d \ n，a）; 
 fclose（fp）; 
} 

和 fsanf 是

  int  t_size; 
 
 FILE * fp; 
 fp = fopen（  xxx.txt，  r）; 
 fscanf（fp， ％d，& t_size）; 
 fclose（fp）; 

解决方案

不确定你的问题是什么 - 你可以这样做（单独的文件句柄用于阅读和写作）： -

  #include   <   stdio.h  >  
  
 main（）
 {
 
  int  t_size; 
 
  FILE * fp_read;  
 fp_read = fopen（  xxx.txt，  r）; 
 fscanf（fp_read， ％d，& t_size）; 
 fclose（fp_read）; 
 
  FILE * fp_write;  
  int  a =  1 ; 
 fp_write = fopen（  test.txt，  w +）; 
 fprintf（fp_write，  int是％d \ n，a）; 
 fclose（fp_write）; 
} 

使您的代码更容易阅读 - 或者您只需关闭然后重新使用文件句柄： -

 main（）
 {
 FILE * fp; 
  int  t_size; 
 
 fp = fopen（  xxx.txt，  r）; 
 fscanf（fp， ％d，& t_size）; 
 fclose（fp）; 
 
  int  a =  1 ; 
 fp = fopen（  test.txt，  w +）; 
 fprintf（fp，  int是％d \ n，a）; 
 fclose（fp）; 
} 

顺便说一下，你的代码中没有显示处理文件结束/错误条件< /块引用>

轻松！只需创建第二个FILE实例：

 FILE * fpInput; 
 FILE * fpOutput; 
 
 fpInput = fopen（  xxx.txt，  r）; 
 fscanf（fpInput， ％d，& t_size）; 
 
 fpOutput = fopen（  yyy.txt，  w +）; 
 fprintf（fpOutput，  int为％d \ n，t_size）; 
 
 fclose（fpInput）; 
 fclose（fpOutput）; 

并且请：删除问题被认为是粗鲁的 - 这对其他人没有帮助类似的问题！

Hi I'm working on a project in C. I want first to open a file called op.txt read the first num of it using fcanf and put the num into a int. Then I want to use another command to write that num into a different file called o.txt

But How can I use a second File command inside the main function which I use the fopen of the first file?

The code for fprint command is

#include <stdio.h> 

main() 
{ 
FILE *fp; 
int a = 1; 
fp = fopen("test.txt", "w+"); 
fprintf(fp, "The int is %d\n", a); 
fclose(fp); 
} 

and for fsanf is

int t_size; 

FILE * fp;	
fp = fopen ("xxx.txt", "r"); 
fscanf(fp, "%d", &t_size); 
fclose(fp);

解决方案

not sure what your issue is - you could do this (separate file handle for reading and writing) :-

#include <stdio.h>

main()
{

int t_size; 
 
FILE *fp_read;	
fp_read = fopen ("xxx.txt", "r"); 
fscanf(fp_read, "%d", &t_size); 
fclose(fp_read);

FILE *fp_write;
int a = 1;
fp_write = fopen("test.txt", "w+");
fprintf(fp_write, "The int is %d\n", a);
fclose(fp_write);
}

that makes your code slightly easier to read - or you could simply close and then re-use the file handle :-

main()
{
FILE *fp;
int t_size; 
 	
fp = fopen ("xxx.txt", "r"); 
fscanf(fp, "%d", &t_size); 
fclose(fp);

int a = 1;
fp = fopen("test.txt", "w+");
fprintf(fp, "The int is %d\n", a);
fclose(fp);
}

btw, no-where in your code do you show handling for end-of-file / error conditions

Easy! Just create a second FILE instance:

FILE* fpInput;
FILE* fpOutput;

fpInput = fopen ("xxx.txt", "r"); 
fscanf(fpInput, "%d", &t_size); 

fpOutput = fopen ("yyy.txt", "w+"); 
fprintf(fpOutput, "The int is %d\n", t_size); 

fclose(fpInput);
fclose(fpOutput);

And please: it's considered rude to remove questions - it doesn't help others with a similar problem!

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