C fprintf 和 fscanf 保存游戏状态

Question

我在使用 fscanf 和 fprintf 时遇到问题，我已将游戏状态保存到文件中，然后尝试从同一个文件中重新加载（下次打开程序时）

我有功能：

bool savegame(saved save) {
    FILE* fptr;
    fptr = fopen("savegame.txt", "w+");
    if (fptr == NULL)
        return 0;
    fprintf(fptr, "beeseed= %d\n", save.beeseed);
    for (int i = 0; i < 5; i++)
    {
        fprintf(fptr, "car %d pos x= %d y=%d\n", i, save.cars[i].pos.x, save.cars[i].pos.y);
        fprintf(fptr, "car %d speed= %d\n", i, save.cars[i].rand);
        fprintf(fptr, "obstacle %d pos x= %d y=%d\n", i, save.obstacles[i].pos.x, save.obstacles[i].pos.y);
        fprintf(fptr, "obstacle %d speed= %d\n", i, save.obstacles[i].rand);
        fprintf(fptr, "frogend %d= %d\n", i, save.frogend[i]);
    }
    fprintf(fptr, "health= %d\n", save.health);
    fprintf(fptr, "worldTime= %f\n", save.worldTime);
    fprintf(fptr, "frog pos x= %d y=%d\n", save.frog.x, save.frog.y);
    fprintf(fptr, "lost frog pos x= %d y= %d rand= %d\n", save.lostfrog.pos.x, save.lostfrog.pos.y, save.lostfrog.rand);
    fprintf(fptr, "score bee= %d score end= %d\n", save.score.bee, save.score.end);
    fprintf(fptr, "score flag= %d score frog= %d\n", save.score.flag, save.score.frog);
    fprintf(fptr, "score pos= %d score total= %d\n", save.score.pos, save.score.total);
    fclose(fptr);
    return 1;
}

这个很好用，我的意思是 - 我的文件正确地填充了值。 现在我尝试扫描这个文件：

bool loadgame(saved* save) {
    FILE* fptr;
    fptr = fopen("savegame.txt", "r");
    if (fptr == NULL)
        return 0;
    fscanf(fptr, "beeseed= %d", &save->beeseed);
    for (int i = 0; i < 5; i++)
    {

    fscanf(fptr, "car %d pos x= %d y=%d", i, &save->cars[i].pos.x, &save->cars[i].pos.y);
    fscanf(fptr, "car %d speed= %d", i, &save->cars[i].rand);
    fscanf(fptr, "obstacle %d pos x= %d y=%d", i, &save->obstacles[i].pos.x, &save->obstacles[i].pos.y);
    fscanf(fptr, "obstacle %d speed= %d", i, &save->obstacles[i].rand);
    fscanf(fptr, "frogend %d= %d", i, &save->frogend[i]);
    }
    fscanf(fptr, "health= %d", &save->health);
    fscanf(fptr, "worldTime= %lf", &save->worldTime);
    fscanf(fptr, "frog pos x= %d y=%d", &save->frog.x, &save->frog.y);
    fscanf(fptr, "lost frog pos x= %d y= %d rand= %d", &save->lostfrog.pos.x, &save->lostfrog.pos.y, &save->lostfrog.rand);
    fscanf(fptr, "score bee= %d score end= %d", &save->score.bee, &save->score.end);
    fscanf(fptr, "score flag= %d score frog= %d", &save->score.flag, &save->score.frog);
    fscanf(fptr, "score pos= %d score total= %d", &save->score.pos, &save->score.total);
    fclose(fptr);
    return 1;
}

它只适用于文件的第一行（即 beeseed= 3），其他的根本不起作用

我知道我可能不太了解 fscanf，但我已经在 google 上检查了很多问题，但我不知道如何使它正确 - 对我来说最重要的是 - 易于理解和可读（我可能可以在一个 fscanf 中完成所有操作，其中包含整个 .txt 文件和变量为 %d，但它看起来很乱）

我也尝试在每个 fscanf 的末尾给出 '\n' 但它会带来库错误

还有我的savegame.txt 文件：

beeseed= 8
car 0 pos x= 952 y=427
car 0 speed= 9
obstacle 0 pos x= 1028 y=217
obstacle 0 speed= 10
frogend 0= 0
car 1 pos x= 647 y=392
car 1 speed= 8
obstacle 1 pos x= 1131 y=182
obstacle 1 speed= 5
frogend 1= 1
car 2 pos x= 604 y=357
car 2 speed= 5
obstacle 2 pos x= -71 y=147
obstacle 2 speed= 5
frogend 2= 0
car 3 pos x= 437 y=322
car 3 speed= 6
obstacle 3 pos x= 320 y=112
obstacle 3 speed= 7
frogend 3= 0
car 4 pos x= 142 y=287
car 4 speed= 5
obstacle 4 pos x= 7 y=77
obstacle 4 speed= 7
frogend 4= 0
health= 5
worldTime= 4.892000
frog pos x= 320 y=462
lost frog pos x= 376 y= 182 rand= 188
score bee= 200 score end= 476
score flag= 0 score frog= 0
score pos= 0 score total= 120

问题可能是我的结构包含布尔值save.frogend[i] 是布尔形式并且需要 %d（也是 1/0）？

typedef struct {
int x;
int y;
}pos;

typedef struct {
    short int pos;
    short int end;
    short int frog;
    short int bee;
    short int total;
    short int flag;
} score;

typedef struct {
    bool frogend[5];
    score score;
    pos frog;
    struct {
        pos pos;
        int rand;
    }lostfrog;
    struct {
        pos pos;
        int rand;
    }obstacles[5];
    struct {
        pos pos;
        int rand;
    }cars[5];
    short int beeseed;
    double worldTime;
    int health;
}saved;

Answer 1

您不会跳过 fscanf() 格式字符串中的换行符。所以第二个fscanf() 会失败，因为它希望在最后一个y=%d 之后立即找到单词car，但是它们之间有一个换行符。

在每个格式字符串的开头放置一个空格。这将使它跳过任何前导空格。

另外，参数中的所有i 都应该是&i。但是您并不想重新分配i，因为它是由for 循环头控制的。因此，您应该跳过将这些字段分配给任何变量；你可以用%*d来做到这一点。

bool loadgame(saved* save) {
    FILE* fptr;
    fptr = fopen("savegame.txt", "r");
    if (fptr == NULL)
        return 0;
    fscanf(fptr, "beeseed= %d", &save->beeseed);
    for (int i = 0; i < 5; i++)
    {

        fscanf(fptr, " car %*d pos x= %d y=%d", &save->cars[i].pos.x, &save->cars[i].pos.y);
        fscanf(fptr, " car %*d speed= %d", &save->cars[i].rand);
        fscanf(fptr, " obstacle %*d pos x= %d y=%d", &save->obstacles[i].pos.x, &save->obstacles[i].pos.y);
        fscanf(fptr, " obstacle %*d speed= %d", &save->obstacles[i].rand);
        fscanf(fptr, " frogend %*d= %d", &save->frogend[i]);
    }
    fscanf(fptr, " health= %d", &save->health);
    fscanf(fptr, " worldTime= %lf", &save->worldTime);
    fscanf(fptr, " frog pos x= %d y=%d", &save->frog.x, &save->frog.y);
    fscanf(fptr, " lost frog pos x= %d y= %d rand= %d", &save->lostfrog.pos.x, &save->lostfrog.pos.y, &save->lostfrog.rand);
    fscanf(fptr, " score bee= %d score end= %d", &save->score.bee, &save->score.end);
    fscanf(fptr, " score flag= %d score frog= %d", &save->score.flag, &save->score.frog);
    fscanf(fptr, " score pos= %d score total= %d", &save->score.pos, &save->score.total);
    fclose(fptr);
    return 1;
}

另一种选择是使用fgets() 读取每一行，然后使用sscanf() 从中提取值。

Answer 2

1. 处理fscanf返回值。处理错误。
2. 您无法扫描到i。启用编译器警告并修复它们。
3. 与其他答案一样，扫描换行符。
4. short int 的格式说明符是 %hd。

至于第2点，做fscanf(fptr, "%d", i)是无效的，i不是一个有效的变量地址。使用%*d，您可以扫描一个整数而不保存结果：

for (int i = 0; i < 5; i++)
{
    int e = fscanf(fptr, " car %*d pos x= %d y=%d", &save->cars[i].pos.x, &save->cars[i].pos.y); 
    if (e != 2) abort();
    ...
}

但我会尽可能实现附加错误处理：

for (int i = 0; i < 5; i++)
{
    int read_i = 0;
    int e = fscanf(fptr, " car %d pos x= %d y=%d", &read_i, &save->cars[i].pos.x, &save->cars[i].pos.y); 
    if (e != 3) abort(); // handle error
    if (i != read_i) abort(); // handle error
    ...
}

问题可能是我的结构包含布尔值 save.frogend[i] 是布尔形式

例如，如果save.frongend[i] 的类型是bool，则需要扫描到具有适当类型的临时变量以匹配scanf 说明符。例如，您可以仅使用 %d 和 int。然后检查这些值是否在适当的范围内。例如：

int temp = 0;
int e = fscanf(fptr, "frogend %*d= %d", &temp);
if (e != 1) abort();
if (temp != 0 && temp != 1) abort();
save->frogend[i] = temp;

我想把它们放在一起：

bool loadgame(saved* save) {
    FILE* fptr;
    fptr = fopen("savegame.txt", "r");
    if (fptr == NULL)
        return 0;
    int e = 0;
    e = fscanf(fptr, "beeseed= %hd", &save->beeseed);
    if (e != 1) return 0;
    for (int i = 0; i < 5; i++) {
        int i2 = 0;
        e = fscanf(fptr, " car %d pos x= %d y=%d", &i2, &save->cars[i].pos.x, &save->cars[i].pos.y);
        if (e != 3) return 0;
        if (i2 != i) return 0;
        e = fscanf(fptr, " car %d speed= %d", &i2, &save->cars[i].rand);
        if (e != 2) return 0;
        if (i2 != i) return 0;
        e = fscanf(fptr, " obstacle %d pos x= %d y=%d", &i2, &save->obstacles[i].pos.x, &save->obstacles[i].pos.y);
        if (e != 3) return 0;
        if (i2 != i) return 0;
        e = fscanf(fptr, " obstacle %d speed= %d", &i2, &save->obstacles[i].rand);
        if (e != 2) return 0;
        if (i2 != i) return 0;
        int temp = 0;
        e = fscanf(fptr, "frogend %d= %d", &i2, &temp);
        if (e != 2) return 0;
        if (i2 != i) return 0;
        if (temp != 0 && temp != 1) return 0;
        save->frogend[i] = temp;
    }
    e = fscanf(fptr, " health= %d", &save->health);
    if (e != 1) return 0;
    e = fscanf(fptr, " worldTime= %lf", &save->worldTime);
    if (e != 1) return 0;
    e = fscanf(fptr, " frog pos x= %d y=%d", &save->frog.x, &save->frog.y);
    if (e != 2) return 0;
    e = fscanf(fptr, " lost frog pos x= %d y= %d rand= %d", &save->lostfrog.pos.x, &save->lostfrog.pos.y, &save->lostfrog.rand);
    if (e != 3) return 0;
    e = fscanf(fptr, " score bee= %hd score end= %hd", &save->score.bee, &save->score.end);
    if (e != 2) return 0;
    e = fscanf(fptr, " score flag= %hd score frog= %hd", &save->score.flag, &save->score.frog);
    if (e != 2) return 0;
    e = fscanf(fptr, " score pos= %hd score total= %hd", &save->score.pos, &save->score.total);
    if (e != 2) return 0;
    fclose(fptr);
    return 1;
}