Question

此程序旨在根据用户的输入显示视频游戏广告资源。用户需要确定循环使用num_of_games运行多长时间。我们必须使用开关循环来确定类型。它编译但无法正确显示。

#include <stdio.h>
#include <string.h>
#define MAX 16

typedef enum genre_type{ action = 0, rpg = 1, simulation = 2, 
                        strategy = 3, sports = 4} genre_t;

typedef struct{
    char title[MAX];
    int num_sold;
    genre_t genre;
}game_s;
// suppose to use functions and enum list for determining the genre
void get_game_info(game_s *ptr);
void display_inventory(game_s game[], int num_of_games);


int
main(void){

    int i=0, num_of_games;
    int c_game=0;
    game_s game[num_of_games];

    printf("How many games are there in inventory? ");
    scanf("%d", &num_of_games);
    fflush(stdin);
    printf("\n");
    while(c_game < num_of_games){
        printf("\n");
        get_game_info(&game[c_game]);
        c_game++;
    }
    printf("\n");
    display_inventory(game, num_of_games);


    return(0);
}
void get_game_info(game_s *ptr)
{       
        int i, str_len, genre, num_sold;

        printf("Title of game <maximum of 15 characters>: ");
        gets(ptr->title);
        str_len = strlen(ptr->title);
            if(str_len >= 15){
                printf("Title will be truncated\n");
                ptr->title[MAX]= '\0';
            }
        printf("Number sold: ");
        scanf("%d", &ptr->num_sold);
        fflush(stdin);
        printf("Genre (0-action, 1-rpg, 2-simulation, 3-strategy, 4-sports): ");
        scanf("%d", &ptr->genre);
        fflush(stdin);
            if(ptr->genre>4){
                printf("Not a valid genre");
        fflush(stdin);  
}
}
void display_inventory(game_s game[], int num_of_games)
{   
    int i, genre;

    printf("Title\t\t\t\t\t\tQuantity Sold\t\t\t\t\t\tGenre");
    printf("\n=====\t\t\t\t\t\t=============\t\t\t\t\t\t=====\n");
    for(i=0; i < num_of_games; i++){
    switch(genre){
        case action: printf("Action"); break;
        case rpg: printf("RPG"); break;
        case simulation: printf("Simulation"); break;
        case strategy: printf("Strategy"); break;
        case sports: printf("Sports"); break;
        default: puts("Not a choice. Try again"); break;

我认为这是造成大部分问题的原因。我不知道我是否正在使用游戏[I] .title和其他人调用结构。我认为问题在于结构调用。如果我使用game_s [I] .title我得到＆＃34;预期表达式＆＃34;错误，如果我使用游戏[I] .title它没有正确打印

    printf("%s\t\t\t\t\t\t%d\t\t\t\t\t\t%s", game[i].title, game[i].num_sold, game[i].genre);
    printf("\n");
    }
    }
}

Answer 1

我认为问题是write，因为send没有启动。

应该是：

recv

Answer 2

你的努力是值得称道的。您提供代码并善意地尝试理解为什么事情不起作用，但不幸的是，您的代码充满了错误。通过尝试使用未初始化的num_of_games声明VLA，您几乎可以立即调用 Undefined Behavior 。无论你从那一点开始在你的代码中做了什么，它只不过是一个骰子卷，无论你是否真的处理了某些东西或SegFaulted。

display_inventory中缺少输出（无论实际内存是什么）是由于printf语句放在switch语句的正文中。如果您break switch的{{1}}只是跳到default案例之下，则会完全跳出switch。因此，即使代码的其余部分是正确的，您也永远不会产生输出。

fflush(stdin)是错误的，并且除了windoze之外都会调用未定义的行为。它仅为世界其他地方的可搜索流定义 - 不使用它。相反，您可以定义一个简单的函数来清空stdin，并根据需要调用它。

编译时，始终使用 编译器警告启用 进行编译，不接受代码，直到干净地编译而不发出警告< / em>的。要启用警告，请将-Wall -Wextra添加到gcc编译字符串中。（添加-pedantic以获得其他几个警告）。对于 VS （windoze上的cl.exe），请添加/Wall。对于clang，请添加-Weverything。阅读并理解每个警告。他们将识别任何问题，以及它们发生的确切线。您可以通过简单地聆听编译器告诉您的内容，从大多数教程中学到很多关于编码的知识。

您的代码中的错误数量过于庞大，无法逐项列出并与每个点说话，因此我在下面列出了注释以解决错误。

#include <stdio.h> #include <stdlib.h> /* for EXIT_FAILURE */ #include <string.h> #define MAX 16 typedef enum genre_type { action = 0, rpg = 1, simulation = 2, strategy = 3, sports = 4 } genre_t; typedef struct { char title[MAX]; int num_sold; genre_t genre; } game_s; // suppose to use functions and enum list for determining the genre void get_game_info (game_s *ptr); void display_inventory (game_s *game, int num_of_games); void fflush_stdin(); int main (void) { int num_of_games, c_game = 0, scnfrtn; /* scanf return - must always check EOF */ printf ("How many games are there in inventory? "); for (;;) { /* loop until valid input or EOF (user cancels) */ if ((scnfrtn = scanf ("%d", &num_of_games)) == 1) { fflush_stdin(); /* manually empty stdin */ break; } else if (scnfrtn == EOF) { /* user cancels? */ fprintf (stderr, "user canceled input.\n"); exit (EXIT_FAILURE); } /* handle error */ fprintf (stderr, "error: invalid input.\n"); fflush_stdin(); } putchar ('\n'); /* don't printf a single-char */ /* declare VLA only AFTER num_of_games has a value */ game_s game[num_of_games]; memset (game, 0, sizeof game); /* optional, zero VLA */ while (c_game < num_of_games) { putchar ('\n'); get_game_info (&game[c_game]); c_game++; } putchar ('\n'); display_inventory (game, num_of_games); return 0; } void get_game_info (game_s *ptr) { int scnfrtn; /* scanf return - must always check EOF */ size_t len = 0; /* strlen return is size_t */ printf ("Title of game <maximum of 15 characters>: "); fgets (ptr->title, MAX, stdin); /* NEVER, NEVER, NEVER use gets */ len = strlen (ptr->title); if (len && ptr->title[len-1] == '\n') /* check for trailing \n */ ptr->title[--len] = '\0'; /* overwrite with nul-character */ else /* warn of truncation */ fprintf (stderr, "error: title too long, truncated.\n"); for (;;) { /* loop until valid input or EOF (user cancels) */ printf ("Number sold: "); if ((scnfrtn = scanf ("%d", &ptr->num_sold)) == 1) { fflush_stdin(); break; } else if (scnfrtn == EOF) { fprintf (stderr, "user canceled input.\n"); exit (EXIT_FAILURE); } fprintf (stderr, "error: invalid input.\n"); fflush_stdin(); } for (;;) { /* loop until valid input or EOF (user cancels) */ printf ("Genre (0-action, 1-rpg, 2-simulation, " "3-strategy, 4-sports): "); if ((scnfrtn = scanf ("%d", (int*)&ptr->genre)) == 1) { fflush_stdin(); break; } else if (scnfrtn == EOF) { fprintf (stderr, "user canceled input.\n"); exit (EXIT_FAILURE); } else if (ptr->genre > 4) /* additional check for genre */ fprintf (stderr, "error: invalid genre.\n"); else fprintf (stderr, "error: invalid input.\n"); fflush_stdin(); } } void display_inventory (game_s *game, int num_of_games) { int i; printf ("%11s%-24s %-24s %s\n=========================" "==============================================\n", " ", "Title","Quantity Sold", "Genre"); for (i = 0; i < num_of_games; i++) { switch (game[i].genre) { case action: printf ("%-11s", "Action"); break; case rpg: printf ("%-11s", "RPG"); break; case simulation: printf ("%-11s", "Simulation"); break; case strategy: printf ("%-11s", "Strategy"); break; case sports: printf ("%-11s", "Sports"); break; default: puts ("Not a choice. Try again"); break; } printf ("%-24s %-24u %d\n", game[i].title, game[i].num_sold, game[i].genre); } } void fflush_stdin() { for (int c = getchar(); c != '\n' && c != EOF; c = getchar()) {} }

（注意：使用printf 最小字段和修饰符来控制间距而不是一堆tabs一起使用）

示例使用/输出

$ ./bin/gamegenre How many games are there in inventory? 3 Title of game <maximum of 15 characters>: first title Number sold: 12 Genre (0-action, 1-rpg, 2-simulation, 3-strategy, 4-sports): 2 Title of game <maximum of 15 characters>: second title Number sold: 13 Genre (0-action, 1-rpg, 2-simulation, 3-strategy, 4-sports): 1 Title of game <maximum of 15 characters>: third title Number sold: 14 Genre (0-action, 1-rpg, 2-simulation, 3-strategy, 4-sports): 3 Title Quantity Sold Genre ======================================================================= Simulation first title 12 2 RPG second title 13 1 Strategy third title 14 3

（注意：我不知道您的genre 描述的目标是什么，因此只需在每个开头输出上面的一行）

仔细看看，如果您有其他问题，请告诉我。

显示结构

2 个答案: