随机变量总是生成5

所以我一直在自学如何编写c++代码。我购买了Michael Dawson写的《Beginning c++ through game programming》第三版，其中有一章是关于循环的。在这一章的末尾，你制作了一款混淆单词的游戏。我想再深入一点，让它随机选择5个单词。但问题是，它总是得到5的值，因此总是选择第5个单词。

代码如下

#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
using namespace std;
int main()
{
    enum fields {WORD, HINT, NUM_FIELDS};
    const int NUM_WORDS = 5;
    const string WORDS[NUM_WORDS][NUM_FIELDS] =
    {
        {"wall", "Do you feel you're banging your head against something?"},
        {"glasses", "These might help you see the answer"},
        {"labored", "Going slowly is it?"},
        {"persistent", "Keep at it"},
        {"jumble", "It's what this game is about!"}
    };
    srand(time(0));
    int preWord = rand() % 3;
    string tempWord;
    string theWord = WORDS[preWord][WORD]; //word to guess
    string theHint = WORDS[preWord][HINT]; //hint for word
    if (preWord = 1)
    {
        theWord = "wall";
        tempWord = "wall";
    }
    if (preWord = 2)
    {
        theWord = "glasses";
        tempWord = "glasses";
    }
    if (preWord = 3)
    {
        theWord = "labored";
        tempWord = "labored";
    }
    if (preWord = 4)
    {
        theWord = "persistent";
        tempWord = "persistent";
    }
    if (preWord = 5)
    {
        theWord = "jumble";
        tempWord = "jumble";
    }
    int length = theWord.size();
    for (int i = 0; i < length; ++i)
    {
            int index1 = (rand() % length);
            int index2 = (rand() % length);
            char temp = theWord[index1];
            theWord[index1] = theWord[index2];
            theWord[index2] = temp;
    }
    cout << "tttWelcome to the Word Jumble!nn";
    cout << "Unscramble the letters to make a word.n";
    cout << "Enter 'hint' for a hint.n";
    cout << "Enter 'quit' to quit the game.nn";
    cout << "The word is: " << theWord;
    cout << "nvariable 'preWord' is: " << preWord;
    string guess;
    cout << "nnYour guess: ";
    cin >> guess;
    while ((guess != tempWord) && (guess != "quit"))
    {
        if (guess == "hint")
        {
            cout << theHint;
        }
        else
        {
            cout << "Sorry, that's not it.";
        }
        cout <<"nnYour guess: ";
        cin >> guess;
    }
    if (guess == tempWord)
    {
        cout << "nThat's it! You guessed it!n";
    }
    cout << "nThanks for playing!n";
    return 0;
}