C언어 질문있습니다

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
char text[100];
 
#define DF_RAIL 100
 
void encrypt(int rail, char *plain);
void decrypt(int rail, char *cipher);
 
void encryptMsg(char msg[], int key);
void decryptMsg(char enMsg[], int key);
 
 
int main()
{
 
	int rail = 0;
        int mode = 0;
        int menu = 0;
 
        rail = 10;
        strcpy(text, "test");
 
	encrypt(rail, text);
	decrypt(rail, text);
 
        encryptMsg(text, rail);
        decryptMsg(text, rail);
 
        return 0;
 
	{
 
		printf("\n =================MENU=================\n");
		printf("\n 1. Encoding // 2. Decoding // 3. Exit\n");
		printf("\n >> Select a mode: ");
//		scanf("%d", &mode);
 
		if (mode == 1)
		{
			printf("\n ============ENCODING MODE=============\n");
 
			printf("\n >> Enter the text: ");
//			scanf("%s", &text);
 
			printf("\n >> Enter the value of rail: ");
//			scanf("%d", &rail);
 
			printf("\n >> Encrypted text: ");
 
			encrypt(rail, text);
		}
 
		else if (mode == 2)
		{
			printf("\n ============DECODING MODE=============\n");
 
			printf("\n >> Enter the text: ");
//			scanf("%s", &text);
 
			printf("\n >> Enter the value of rail: ");
//			scanf("%d", &rail);
 
			decrypt(rail, text);
		}
 
		else if (mode == 3)
		{
			return 0;
		}
 
		else
			return 1; //main();
 
	}
 
	printf("\n\n Return to main menu? (0. No // 1. Yes)");
	printf("\n Your choice: ");
//	scanf("%d", &menu);
 
	if (menu == 1)
		return 1; //main();
 
	else
		printf("THE END!\n\n");
	return 0;
 
}
 
void encryptMsg(char msg[], int key)
{
    int msgLen = strlen(msg), i, j, k = -1, row = 0, col = 0;
    char railMatrix[DF_RAIL][100];
 
    for(i = 0; i < key; ++i)
        for(j = 0; j < msgLen; ++j)
            railMatrix[i][j] = '\n';
 
    for(i = 0; i < msgLen; ++i){
        railMatrix[row][col++] = msg[i];
 
        if(row == 0 || row == key-1)
            k= k * (-1);
 
        row = row + k;
    }
 
    cout<<"\nEncrypted Message: ";
 
    for(i = 0; i < key; ++i)
        for(j = 0; j < msgLen; ++j)
            if(railMatrix[i][j] != '\n')
                cout<<railMatrix[i][j];
}
 
 
void encrypt(int rail, char *plain)
{
 
	char railfence[DF_RAIL ][100], buf[2];
	int i;
        int max;
	int number = 0, increment = 1;
	buf[1] = '\0';
 
	for (i = 0; i<rail; i++)
		railfence[i][0] = '\0';
 
        max = strlen(plain);
	for (i = 0; i<max; i++)
	{
 
		if (number + increment == rail)
			increment = -1;
 
		else if (number + increment == -1)
			increment = 1;
 
		buf[0] = plain[i];
		strcat(railfence[number], buf);
		number += increment;
 
	}
 
	for (i = 0; i<rail; i++)
		printf("%s", railfence[i]);
 
}
 
void decryptMsg(char enMsg[], int key)
{
    int msgLen = strlen(enMsg), i, j, k = -1, row = 0, col = 0, m = 0;
    char railMatrix[DF_RAIL][100];
 
    for(i = 0; i < key; ++i)
        for(j = 0; j < msgLen; ++j)
            railMatrix[i][j] = '\n';
 
    for(i = 0; i < msgLen; ++i){
        railMatrix[row][col++] = '*';
 
        if(row == 0 || row == key-1)
            k= k * (-1);
 
        row = row + k;
    }
 
    for(i = 0; i < key; ++i)
        for(j = 0; j < msgLen; ++j)
            if(railMatrix[i][j] == '*')
                railMatrix[i][j] = enMsg[m++];
 
    row = col = 0;
    k = -1;
 
    cout<<"\nDecrypted Message: ";
 
    for(i = 0; i < msgLen; ++i){
        cout<<railMatrix[row][col++];
 
        if(row == 0 || row == key-1)
            k= k * (-1);
 
        row = row + k;
    }
}
 
 
void decrypt(int rail, char *cipher)
{
	int cipherlength = strlen(cipher);
	int j;
	int counter = 0;
	int number = 0;
	int increment = 1;
	int railfence[DF_RAIL][100];
	int i;
	int count[100];
 
 
 
	for (i = 0; i<cipherlength; i++)
		count[i] = 0;
 
	for (i = 0; i<cipherlength; i++)
	{
 
		if (number + increment == rail)
			increment = -1;
 
		else if (number + increment == -1)
			increment = 1;
 
		railfence[number][count[number]] = i;
		++count[number];
		number += increment;
 
	}
 
	char buffer[1000];
        memset(buffer, 0x00, 1000);
 
	for (i = 0; i<rail; i++)
		for (j = 0; j<count[i]; j++)
		{
 
			buffer[railfence[i][j]] = cipher[counter];
			++counter;
 
		}
 
	buffer[cipherlength] = '\0';
	printf("\n >> Decrypted text: %s\n", buffer);
 
}