c - 根据规则对从文件中读取的文本进行标记

Question

我有一个编写代码的作业，其中应该读取一个文本文件，然后编写一个输出文件，显示代码中每个参数的频率，即“整数= 2，关键字= 13，标识符= 3。 ..”

我写了一个代码，但我面临的问题是它总是将所有频率输出为 0。好像“integer++”和其他增量不起作用。

你能告诉我我在这里做错了什么吗？

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

int main(void)
{

   FILE *input; //file to read from
   FILE *output; //file to write to
   char *token=NULL;
   int keywords=0, identifier=0, integer=0, real=0, relationOperator=0, ArtOperator=0, lPar=0, rPar=0, semicolon=0, assign=0, comma=0, etc=0; 


   input = fopen("input.txt", "r"); //read from file
   if (input==NULL) {
             printf("I couldn't open input.txt for reading.\n");
             exit(0);
          }

   token=strstr(input, " "); //tokenize

        while (token!=NULL) //start of loop
        {
                if(token=="%s"){
                    if(token=="main"||"a"||"b"){ //if identifier
                        identifier++;
                    }
                    else{ //if keyword
                        keywords++; 
                    }
                  }
                else if(token=="%d"){ //if integer
                    integer++;
                  }
                else if(token=="%f"){ //if real number
                    real++;
                  }
                else if(token==">"||"<"){ //if relation operator
                    relationOperator++;
                  }
                else if(token=="+"||"-"||"*"||"/"){ //if arithmetic operator
                    ArtOperator++;
                  }
                else if(token=="("){ //if left parenthesis
                    lPar++;
                  }
                else if(token==")"){ //if right parenthesis
                    rPar++;
                  }
                else if(token==";"){ //if semicolon
                    semicolon++;
                  }
                else if(token=="="){ //if assignment operator
                    assign++;
                  }
                else if(token==","){ //if comma
                    comma++;
                  }
                else
                { //consider anything else as etc
                    etc++;
                  }
        token=strtok(NULL, " ");
   }//end of loop

   output = fopen("output.txt", "w"); //write to file

       if (output == NULL) {
             printf("I couldn't open output.txt for writing.\n");
             exit(0);
          }

         fprintf(output, "keywords = %d\n" ,keywords);
         fprintf(output, "identifiers = %d\n" ,identifier);
         fprintf(output, "integers = %d\n" ,integer);
         fprintf(output, "real numbers = %d\n" ,real);
         fprintf(output, "relation operators = %d\n" ,relationOperator);
         fprintf(output, "arithmetic operator = %d\n" ,ArtOperator);
         fprintf(output, "left parenthesis = %d\n" ,lPar);
         fprintf(output, "right parenthesis = %d\n" ,rPar);
         fprintf(output, "semicolons = %d\n" ,semicolon);
         fprintf(output, "assignment operators = %d\n" ,assign);
         fprintf(output, "commas = %d\n" ,comma);
         fprintf(output, "other characters = %d\n" ,etc);

         fclose(output); //close output file

   return 0;
}

Answer 1

乍一看你的代码，我很惊讶它竟然能编译。即使确实如此，表格线:

if(token=="+"||"-"||"*"||"/")

不要做你认为他们做的事情，你应该将 if 语句重写为

if (*token == '+' || *token == '-' || ... || *token == '/')

token 是一个指针，因此您需要比较它的值，当然，并对条件语句使用正确的语法。