編譯器警告，打開文件

#include <stdlib.h> 
#include <stdio.h> 
#include <getopt.h> 
#include "mylib.h" 
#include "tree.h" 

/* A boolean type which can be TRUE or FALSE */ 
typedef enum bool_e {FALSE, TRUE} bool_t; 

static void usage(char *progname); 
static void setup(int argc, char **argv, char **filename, bool_t *rbt, 
        bool_t *do_depth, bool_t *p_order, bool_t *output_graph); 
static void make_graph(char *filename, tree t); 

static void usage(char *prog_name) { 
    fprintf(stderr, "Usage: %s [OPTION]... <STDIN>\n\n%s%s", prog_name, 
      "Perform various operations using a hash-table. By default read\n" 
      "words from stdin and print them with their frequencies to stdout.\n\n" 
      " -d  prints the tree depth\n" 
      " -p  prints the tree in pre_order\n" 
      " -o FILENAME prints output to a specified file\n\n" 
      " -r  creates a rbt tree\n" 
      " -h  Display this message\n\n"); 
} 

static void print_key(char *key) { 
    printf("%s\n", key); 
} 

static void make_graph(char *filename, tree t) { 
    FILE *file = fopen(filename, "w"); 
    fprintf(stderr, "Creating dot file '%s'\n", filename); 
    tree_output_dot(t, file); 
    fclose(file); 
} 



/** 
* Handle options given on the command-line by setting a number of 
* variables appropriately. May call usage() if incorrect arguments 
* or -h given. 
* 
* @param argc the number of command-line arguments. 
* @param argv an array of strings contain the command-line arguments. 
* @param rbt is created if -r is given 
* @param the tree depth is printed if d is given 
* @param tree_outputfile_dot is called if -o output-filename is given 
*/ 

int main(int argc, char **argv) { 
    bool_t rbt = FALSE, do_depth = FALSE, p_order = FALSE, output_graph = FALSE; 
    tree_t tree_type = BST; 
    tree t; 
    char word[256]; 
    char *dot_filename; 

    setup(argc, argv, &dot_filename, &rbt, &do_depth, &p_order, &output_graph); 
    if (rbt) { 
    t = tree_new(RBT); 
    } else { 
     t = tree_new(tree_type); 
    } 
    while ((getword(word, sizeof word, stdin)) != EOF) { 
     t = tree_insert(t, word); 
    } 

    if (do_depth) { 
     printf("%d\n", tree_depth(t)); 
    } else if (p_order) { 
     tree_preorder(t, print_key); 
    } else if (output_graph) { 
     make_graph(dot_filename, t); 
    } else { 
     tree_inorder(t, print_key); 
    } 


    t = tree_free(t); 
    return EXIT_SUCCESS; 
} 


static void setup(int argc, char **argv, char **filename, bool_t *rbt, 
        bool_t *do_depth, bool_t *p_order, bool_t *output_graph) { 
    const char *optstring = "do:prh"; 

    char option; 

    while ((option = getopt(argc, argv, optstring)) != EOF) { 
     switch (option) { 
     case 'd': 
     *do_depth = TRUE; 
     break; 
     case 'o': 
     *filename = optarg; 
     *output_graph = TRUE; 
     break; 
     case 'p': 
     *p_order = TRUE; 
     break; 
     case 'r': 
     *rbt = TRUE; 
     break; 
     case 'h': 
     default: 
     usage(argv[0]); 
     exit(EXIT_SUCCESS); 
     } 
    } 
}

大家好，我試圖編譯這段代碼，並且遇到了一個我不知道如何解決的問題。我的文件有一個警告編譯，我想補救它。編譯器警告，打開文件

的main.c：在函數「主」：的main.c：56：警告：「dot_filename」可用於初始化在這個函數

我真的不知道我將如何得到解決這個固定問題，我通常不會經常使用文件打開的東西，而且我也不確定該怎麼做。我會做什麼來使這個警告消失？

來源

2012-09-30 courtney

找到你聲明「dot_filename」的地方，並給它一個初始值？ 'char * dot_filename = NULL';當然，在你嘗試*使用它之前，實際上*分配*）;） – paulsm4

您可以簡單地用空指針初始化dot_filename。

char *dot_filename = NULL;

這應該修復警告。

來源

2012-09-30 08:55:07

編譯器警告，打開文件

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