c - 努力按整数搜索文件中的结构数组

Question

我正在执行一项主要任务，并且我真的很难从文件中的数组中提取结构。我不知道我的代码从这里到哪里去，因为我没有太多使用 C 的经验。

我正在尝试搜索文件寻找“Robot_Number”(最左边的整数)，然后打印所有特定的机器人信息。我的代码编译并运行，但不会从 while 循环中打印任何内容 (Ln57-66)。 .txt 文件也没有明显的问题。

我的 .txt 文件的布局如下:

1 Bender 2054 30.500000 80 60 0.000000
2 Crusher 1979 15.000000 86 80 0.000000
3 Sprinter 2042 45.000000 41 30 0.000000
4 Vulc4n 2178 47.000000 90 50 0.000000

我的代码:

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

#define RobMax 10

typedef struct {
    int Robot_Number;
    char Robot_Name[20];
    int Year_Manufactured;
    float Top_Speed;
    int Strength;
    int Mass;
    float Best_Score;
 }robot_t;

int main(){
int targetNumber;
int RobCounter = 4;

//create an array of struct, 
robot_t robot_info[RobCounter] = 
{{1, "Bender", 2054, 30.5, 80, 60, 0},
{2, "Crusher", 1979, 15, 86, 80, 0},
{3, "Sprinter", 2042, 45, 41, 30, 0}, 
{4, "Vulc4n", 2178, 47, 90, 50, 0}};


//opening a file for reading and writing
FILE* file =fopen("Robot.txt", "r+w");
if(file ==NULL){
    printf("ERROR: file failed to open!\n");
    exit(-1);
}

/*//Initialising the .txt file, first time only
for (i=0; i<4; i++){
    fprintf(file, "%d %s %d %f %d %d %f\n", 
    robot_info[i].Robot_Number, 
    robot_info[i].Robot_Name, 
    robot_info[i].Year_Manufactured, 
    robot_info[i].Top_Speed, 
    robot_info[i].Strength, 
    robot_info[i].Mass, 
    robot_info[i].Best_Score);

}*/

        printf("you selected search a robot by number. (Type 0 to view all avalible robots)\n");
        scanf("%d", &targetNumber);

        int RNo, YM, S, M;
        char RNa[20];
        float TS, BS;

        if (targetNumber != 0){
            printf("Robot ID: %d's information:\n", targetNumber);
            while( fscanf(file, "%d%19s%d%f%d%d%f", &RNo, RNa, &YM, &TS, &S, &M, &BS) ==2) {
                robot_info[targetNumber].Robot_Number = RNo;
                strcpy(robot_info[targetNumber].Robot_Name, RNa);                       
                robot_info[targetNumber].Year_Manufactured = YM;
                robot_info[targetNumber].Top_Speed = TS;
                robot_info[targetNumber].Strength = S;
                robot_info[targetNumber].Mass = M;
                robot_info[targetNumber].Best_Score = BS;
                printf("Num: %d, Name: %19s, Manufactured: %d, Top Speed: %f, Strength: %d, Mass: %d, Best Score: %f.", RNo, RNa, YM, TS, S, M, BS);
                }   
        }   
fclose(file);

return 0;
}

Answer 1

一些需要考虑的注意事项，如评论部分所述:

• 当您打算从文件中读取包含机器人信息的结构体数组时，为什么要使用它们？
• 当您实际上只是读取文件时，为什么要使用 r+w 打开文件？

因此，假设您没有有关机器人的这些信息，而您只想读取该文件。如果这是最初的意图，这里有一个片段，可能会对您有所帮助。

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

#define RobMax 10

typedef struct {
    int Robot_Number;
    char Robot_Name[20];
    int Year_Manufactured;
    float Top_Speed;
    int Strength;
    int Mass;
    float Best_Score;
}robot_t;

int scan_file(const char* fname, robot_t* robot_info, const int N)
{
    int counter = 0;

    // opening a file for reading
    // Note the change in file open mode as you
    // do not need to write it
    FILE* file = fopen(fname, "r");
    if(file == NULL)
    {
        printf("ERROR: file failed to open!\n");
        return 0;
    }

    int RNo, YM, S, M;
    char RNa[20];
    float TS, BS;


    // Note the change in scan format - you need to include the correct delimiters
    // in your case the white spaces. Also changed 2 -> 7 as you'd expect 7 values
    // to be read and not 2
    int scanres;
    while((scanres = fscanf(file, "%d %19s %d %f %d %d %f", &RNo, RNa, &YM, &TS, &S, &M, &BS)) == 7 && scanres != EOF)
    {
        // if we reached maximum capacity
        if (counter >= N)
            break;

        robot_info[counter].Robot_Number = RNo;
        strcpy(robot_info[counter].Robot_Name, RNa);
        robot_info[counter].Year_Manufactured = YM;
        robot_info[counter].Top_Speed = TS;
        robot_info[counter].Strength = S;
        robot_info[counter].Mass = M;
        robot_info[counter].Best_Score = BS;
        printf("SCANNED: Num: %d, Name: %19s, Manufactured: %d, Top Speed: %f, Strength: %d, Mass: %d, Best Score: %f.\n", RNo, RNa, YM, TS, S, M, BS);

        ++counter;
    }

    fclose(file);

    return counter;
}

// gets the robot's index in the robots array by ID
int get_roboti_by_id(const int ID, const robot_t* robots, const int N)
{
    for (int i = 0; i < N; ++i)
    {
        if (robots[i].Robot_Number == ID)
        {
            return i;
        }
    }

    return -1;
}

void print_info(const robot_t* info)
{
    printf("Num: %d, Name: %19s, Manufactured: %d, Top Speed: %f, Strength: %d, Mass: %d, Best Score: %f.",
           info->Robot_Number, info->Robot_Name, info->Year_Manufactured, info->Top_Speed, info->Strength, info->Mass, info->Best_Score);
}

int main()
{
    int targetNumber;
    int RobCounter;

    // create an array of struct,
    robot_t robot_info[RobMax];


    printf("you selected search a robot by number. (Type 0 to view all avalible robots)\n");
    scanf("%d", &targetNumber);
    // scans the whole file populated with robots
    RobCounter = scan_file("robots.txt", robot_info, RobMax);


    if (targetNumber != 0)
    {
        int robot_index = get_roboti_by_id(targetNumber, robot_info, RobCounter);
        if (robot_index >= 0)
        {
            print_info(&robot_info[robot_index]);
            printf("\n");
        }
        else
        {
            printf("There is no such robot with index: %d\n", targetNumber);
        }
    }
    else
    {
        for (int i = 0; i < RobCounter; ++i)
        {
            print_info(&robot_info[i]);
            printf("\n");
        }
    }

    return 0;
}

如果您发现任何错误或者这不是您所需要的，请随时纠正我。如有任何建议，我们将不胜感激!