Question

我有以下代码正在运行，但在每一行中定义一个变量有点烦人：

char *argv[100];
int argc = 0;
argv[0] = "test";
argc = 1;
char verbose[4], source[20], target[20];
int linenum=0;
while(fgets(line, 256, file) != NULL)
{
    char arg[20], value[20];
    if(line[0] == '#' || strlen(line) < 6) continue;
    linenum++;
    if(sscanf(line, "%[^=]=%s", arg, value) != 2)
    {
        fprintf(stderr,"Syntax error: %s\n",line);
        continue;
    }
    if (value && strcmp(arg,"verbose")==0) {
        strncpy(verbose,value,sizeof(verbose) - 1);
        argv[argc++] = "-v";
        argv[argc++] = verbose;
        //argv[argc++] = value; //not working, shows 0
    }

    if (value && strcmp(arg,"source")==0) {
        strncpy(source,value,sizeof(source) - 1);
        argv[argc++] = "-s";
        argv[argc++] = source;
    }

    if (value && strcmp(arg,"target")==0) {
        strncpy(target,value,sizeof(target) - 1);
        argv[argc++] = "-t";
        argv[argc++] = target;
    }

    //and so on
    |
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}

如何从循环内部将“值”复制到单个char？我的意思是避免使用strncpy()。

Answer 1

你可以使用这样的表：

int source_checker(char *value) { /* .... */; return 0; }
int verbose_checker(char *value) { /* .... */; return 0; }
int target_checker(char *value) { /* .... */; return 0; }

typedef int (*checker_function)(char *); 
const char *label_table[] = { "source", "verbose", "target", 0 };
checker_function checker_table[] = { source_checker, verbose_checker, 
    target_checker, 0 };

typedef enum { tk_source, tk_verbose, tk_target, tk_END } token;


while(fgets(line, 256, file) != NULL)
{
    // ...
    for (size_t i = tk_source; i < tk_END; i++) {
      if (value && strcmp(arg, label_table[i]) == 0) {
          if (checker_table[i](value)) {
            break;
          }
      }
    }

Answer 2

您可以为每个if条件使用循环，并将不同的值存储在预先填充的数组中。

Answer 3

如果您尝试保存几行代码，则可以执行此操作

#include <string.h>

....
char* tempstrings[100];
int temps=0;
..

if (value && strcmp(arg,"verbose")==0) {
    argv[argc++] = "-v";
    argv[argc++] = tempstrings[temps++] = strdup(value);
}

...

// at the end of the program, clean up all the temporary strings
for(int i=0;i<temps;i++) free(tempstrings[i];

将char []写入数组

3 个答案: