c - 如何在文件中查找字符串？

Question

我是 C 语言的新手，最近完成了我的文件工作。我试图创建一个程序来查找文件中输入的名称，但它不起作用。你能尝试修复它吗？我会很感激。

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

int main()
{
    FILE *fr;
    int i,p,counter,final,length,j,c,k = 0;
    char name[256];
    char buffer[1024];

    fr = fopen("C:/Users/prixi/Desktop/HESLA.TXT","r");
    while ((c = fgetc(fr)) != EOF)
        counter++;

    printf("Enter the name");
    scanf("%s",&name);
    length = strlen(name);

    while (fscanf(fr, " %1023[^\n]", buffer) != EOF) {
        for (i = 0; i <= counter; i++)
            if (name[0] == buffer[i]){
                for (j = 0;j < length; j++ )
                    if (name[j] == buffer[i+j])
                        p++;
                    else
                        p = 0;

              /* The 2nd condition is there because after every name there is ' '. */
              if (p == length && buffer[i+j+1] == ' ')
                  final = 1;
          }
     }

     if ( final == 1 )
         printf("its there");
     else
         printf("its not there"); 
return 0;
}

它将文件的内部加载到缓冲区，然后根据文件的长度逐个字符地扫描。我知道它效率低且速度慢，但我只学习 C 大约 4 天。我真的很希望你帮我修复我自己的代码，否则 :D 我可能无法休眠。

Answer 1

有很多方法可以将字符串搜索到文件中。试试这个:

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

char *loadFile(const char *fileName);

int main (void) {
    const char *fileName = "test.txt";
    const char *stringToSearch = "Addams";
    char *fileContent = loadFile(fileName);

    if (strstr(fileContent, stringToSearch)){
        printf("%s was Found\n",stringToSearch);
    }else{
        printf("%s was not Found\n",stringToSearch);
    }

    free(fileContent);

    return 0;
}

char *loadFile(const char *fileName){
    size_t length,size;
    char *buffer;
    FILE *file;

    file = fopen (fileName , "r" );
    if (file == NULL){
        printf("Error fopen, please check the file\t%s\n",fileName);
        exit(EXIT_FAILURE);
    }


    fseek (file , 0 , SEEK_END);
    length = (size_t)ftell (file);
    fseek (file , 0 , SEEK_SET);

    buffer = malloc(length+1);
    if (buffer == NULL){
        fputs ("Memory error",stderr);
        exit (2);
    }

    size = fread (buffer,1,length,file);
    if (size != length){
        fputs ("Reading error",stderr);
        exit(3);
    }
    buffer[length] = '\0';

    fclose (file);
    return buffer;
}

输出:

Addams was Found

我在文件“test.txt”中有以下内容:

Michael Jackson
Bryan Addams
Jack Sparrow