Write char[] to array - c

Question

I have the following code which is working but it's kinda annoying to define a variable in each and every line:
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
|
|
|
|
}
How can I copy to a single char the "value" from inside the loop ? I mean by avoiding the usage of strncpy().

Answer 1

You can use a table like this:
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

You can use a loop for each of your if conditions, and store the differing values in arrays populated beforehand.

Answer 3

If you are trying to save a few lines of code, you could do this
#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];