c - 奇怪的扫描问题

Question

我正在尝试完成一个将字符串与文本文件进行比较的家庭作业程序，因此用户基本上可以在文本文件中搜索文件中的搜索词(字符串)。我到了:)

但是今天我遇到了一个非常奇怪的问题。当它要求搜索术语时，我输入了文本，但它永远不会结束。我可以整天打字，但它仍然要求输入。我忽略了什么奇怪的问题？一双新鲜的眼睛可能会有所帮助:)

/*
 ask the user for a word
 convert user word to LOWER CASE
 open output file
 open input file
 test to be sure input file is open
 search for target word and keep count --> how??
 print results to monitor
 write results to file
 close files
 */
#include<stdio.h>
#include<stdlib.h>

int main (void)
{
    //declare 
    int i =0;
    int count = 0;

    /*************************************************************
     working with arrays and strings
    *************************************************************/
    char mystring[50]; //what user puts in
    char target[50]; //the word in the file we are looking for

    printf("input your message ");
    scanf("%s", mystring);
    //printf("%s", mystring);


    /*************************************************************
     find file, write to it, output the string, end and close file
    **************************************************************/

    //define text file to use
    FILE *cfile;
    //name of file == file
    cfile = fopen("./thanksgiving_proclamation.txt", "a");

    //error handling if file does not exist
    if(cfile == NULL) printf("Cannot open file");

    /*************************************************************
             parse through file and search for string
    **************************************************************/ 
    //convert string to lowercase
    for(i = 0; i < /*strlen(mystring)*/ 500; i++)//convert to string length
    {
        if(target[i] >= 'A' && target[i] <='Z')
            //convert char between a and z into lowercase
            target[i] = target[i] + 32; //makes uppercase char
    }

    //compare our strings
    do{
        //scan through file
        fscanf(cfile, "%s", mystring);  

        //convert string to lowercase
        for(i = 0; i < /*strlen(mystring)*/ 300; i++)//convert to string length
        {
            if(mystring[i] >= 'A' && mystring[i] <='Z')
                //convert char between a and z into lowercase
                mystring[i] = mystring[i] + 32; //makes uppercase char
        }
        if(strcmp(mystring, target) == 0)
            count++;
    }while(!feof(cfile));

    //while(strcmp(target,"quit")!=0)//end loop


    //print to file
    fprintf(cfile, "%s", mystring);

    //close file
    fclose(cfile);

    //show user file has been written
    printf("\nSuccess. File has been written\n");


    printf("Press Enter to Continue...");
    getchar();
    return 0;
}

Answer 1

您以追加模式打开文件:

cfile = fopen("...", "a");

然后您尝试从中读取。

fscanf(cfile, "%s", mystring);

对于解决问题的第一次尝试，我会尝试打开文件进行读取，在循环内从中读取文件并关闭文件。然后再次打开它，这次是为了在其中添加 mystring(并 fclose 它)。

一旦成功，如果你愿意，试试看在“阅读和附加模式”下打开是否有效......

cfile = fopen("...", "a+");