尝试删除空格时C代码出错

Question

这段代码是词法分析器的基础，它执行从源文件中删除空格的基本操作，并将其重写为另一个文件，每个单词都在不同的行中。 但是我无法理解为什么文件lext.txt没有更新？

#include<stdio.h>

/* this is a lexer which recognizes constants , variables ,symbols, identifiers , functions , comments and also header files . It stores the lexemes in 3 different files . One file contains all the headers and the comments . Another file will contain all the variables , another will contain all the symbols. */

int main()
{
    int i;
    char a,b[20],c;
    FILE *fp1,*fp2;

    fp1=fopen("source.txt","r"); //the source file is opened in read only mode which will passed through the lexer
    fp2=fopen("lext.txt","w");  
    //now lets remove all the white spaces and store the rest of the words in a file 

    if(fp1==NULL)
    {
        perror("failed to open source.txt");
        //return EXIT_FAILURE;
    }
    i=0;
    while(!feof(fp1))
    {


        a=fgetc(fp1);

        if(a!="")
        {
            b[i]=a;
        printf("hello");
        }
        else
        {

            b[i]='\0';
            fprintf(fp2, "%.20s\n", b);
            i=0;
            continue;
        }
        i=i+1;                  

        /*Switch(a)
        {
            case EOF :return eof;
            case '+':sym=sym+1;

            case '-':sym=sym+1;

            case '*':sym=sym+1;

            case '/':sym=sym+1;

            case '%':sym=sym+1;

            case '
        */
    }
return 0;
}

Answer 1

仅在此条件失败时才写入文件：

if(a!="") // incorrect comparison..warning: comparison between pointer and integer

从未这样做过，你永远不会去else部分。

将测试更改为：

if(a!=' ')

修改

当您到达文件末尾时，您只需终止程序而不编写数组b中的内容。因此，在while循环之后需要另一个fprintf：

} // end of while loop.
b[i]='\0';
fprintf(fp2, "%.20s\n", b);

好的，这里的代码经过测试并且工作正常：）

while(1)
{
    a=fgetc(fp1);
    if(feof(fp1))
        break;

    if(a!=' ')
        b[i++]=a;
    else {    
        b[i]='\0';
        fprintf(fp2, "%.20s\n", b);
        i=0;
    }    
}
b[i]='\0';
fprintf(fp2, "%.20s\n", b);

Answer 2

你忘了冲！ （除其他外......）:- P

---

  

if（a！=''）

和

  

//将待处理数据写入文件

     

fflush（）;

和

  

//释放文件指针

     

FCLOSE（FP2）;

这是完整的代码：

#include<stdio.h>

/* this is a lexer which recognizes constants , variables ,symbols, identifiers , functions , comments and also header files . It stores the lexemes in 3 different files . One file contains all the headers and the comments . Another file will contain all the variables , another will contain all the symbols. */

int main()
{
    int i;
    char a,b[20],c;
    FILE *fp1,*fp2;

    fp1=fopen("source.txt","r"); //the source file is opened in read only mode which will passed through the lexer
    fp2=fopen("lext.txt","w");  
    //now lets remove all the white spaces and store the rest of the words in a file 

    if(fp1==NULL)
    {
        perror("failed to open source.txt");
        //return EXIT_FAILURE;
    }
    i=0;
    while(!feof(fp1))
    {


        a=fgetc(fp1);

        if(a!=' ')
        {
            b[i]=a;
            printf("hello");
        }
        else
        {

            b[i]='\0';
            fprintf(fp2, "%.20s\n", b);
            i=0;
        }
        i=i+1;

        //writes pending data to file
        fprintf(fp2, "%.20s\n", b);
        fflush();

        //Releases file-pointer
        fclose(fp2);   

        /*Switch(a)
        {
            case EOF :return eof;
            case '+':sym=sym+1;

            case '-':sym=sym+1;

            case '*':sym=sym+1;

            case '/':sym=sym+1;

            case '%':sym=sym+1;

            case '
        */
    }
return 0;
}

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