c代写：cs50 c programming assignment6

• Work on an assignment by yourself without sharing the answer to a classmate. (It is great that students study together but an assignment is an individual task. It is not a group project.)
• Start to do an assignment early and ask the teacher if you have a question.
• Add a comment with your name at the top of your source code
• Put all your files that you want to submit into one zip file
• Your folder should have your last name, first name, your class and assignment number. Example: rattanasook_hathairat_cs50_6.zip

Write a program that merges two files as follows. The two files are in the docsharing which you can download it.
One file will contain usernames (usernames.txt):

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foster001
smith023
nyuyen002
…

The other file will contain passwords (passwords.txt):

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x34rdf3e
p43e4rdd
w32eds22
…

The program should create a third file matching username and passwords (usernamesPasswords.txt):

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foster001 x34rdf3e
smith023 p43e4rdd
nyuyen002 w32eds22
… …

Give the user of your programs the option of displaying you output file.

下边是完整实现

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#include <stdlib.h>
#include <string.h>

#define USERNAME_FILE "usernames.txt"
#define PASSWORD_FILE "passwords.txt"

#define COMBINE_FILE "usernamesPasswords.txt"

int (int argc, char *argv[]){
	int display; 
	FILE* u_file; // File handler to username
	FILE* p_file; // File handler to password
	FILE* o_file; // File handler to output file
	char line_u[128];
	char line_p[128];
	char line_o[512];

	if(argc == 2 && strcmp(argv[1], "-s") == 0){
		display = 1;
	}else{
		printf("You can add -s option to display output.n");
		display = 0;
	}

	// Open file
	u_file = fopen(USERNAME_FILE, "r");
	p_file = fopen(PASSWORD_FILE, "r");
	o_file = fopen(COMBINE_FILE, "w");

	// Read file line by line
	while(!feof(u_file)){
		fgets(line_u, 128, u_file);
		fgets(line_p, 128, p_file);

		// Replace 'n' to '