Why is argc even involved in this? argc is the number of arguments (each is a string) used to execute the program. argv is the program name. argv is the first string that follows, and so on. You need to understand that argv is an array of strings, not a single string (i.e., an array of chars.) So, if a program is executed with 4 parameters, then argc would be 5 and argv would be an array of 5 strings.
You need to use a for loop to step through the string argv to check each char. To do that, you need to realize that argv is a 2 dimensional array and you're checking all the chars in one row. Think in terms of argv[i]. The for loop needs to run from 0 to strlen(argv).
Hopefully, this explains it in enough detail that you can figure out how to code it.
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