C++二维数组温度记录程序异常：警告及输出内存地址问题求助

Hey there! As someone who’s navigated the C++ learning curve after starting with Python/JS, I totally get where you’re stuck. Let’s break down your issues one by one and get that temperature program working right.

First: Why Are You Seeing Memory Addresses Instead of Temperatures? #

Unlike Python or JavaScript, where printing an array directly shows its elements, C++ treats array names as pointers to the first element of the array. So if you tried something like cout << monthlyTemps;, you’re just printing the memory location where your 2D array starts—not the actual temperature values.

The Fix: Loop Through the 2D Array #

You need nested loops to access each temperature value in your 12-month, high/low array. Here’s how to do it properly:

// Assume your array is defined like this: double temps[12][2];
for (int month = 0; month < 12; ++month) {
    cout << "Month " << month + 1 << ": "
         << "High = " << temps[month][0] << ", "
         << "Low = " << temps[month][1] << endl;
}

This loops through each month, then accesses the first index (high temp) and second index (low temp) for that entry.

Second: Fixing the "Assign Return Value to New Variables" Warning #

This warning pops up when you call a function that returns a value but don’t use that return value. For your temperature program, this is almost certainly related to cin (since you’re inputting temperatures).

cin returns an istream& object that tells you whether the input operation succeeded. If you just write cin >> temps[month][0];, the compiler notices you’re ignoring that return value—and flags it with a warning.

Two Ways to Fix This Warning #

1. Use the return value for input validation (recommended)
   This isn’t just about silencing the warning—it makes your program more robust. Check if the input was valid:

   cout << "Enter high temp for month " << month + 1 << ": ";
   if (!(cin >> temps[month][0])) {
       cerr << "Whoops, that's not a valid number!" << endl;
       return 1; // Exit with error code
   }
   

2. Explicitly ignore the return value (quick fix)
   If you just want to get rid of the warning without adding validation, you can cast the return value to void:

   static_cast<void>(cin >> temps[month][0]);
   

A Full Working Example #

Putting it all together, here’s a complete snippet that should behave as expected:

#include <iostream>
using namespace std;

int main() {
    // 2D array: 12 months, each with [high temp, low temp]
    double monthlyTemps[12][2];

    // Input phase
    for (int month = 0; month < 12; ++month) {
        cout << "=== Month " << month + 1 << " ===" << endl;
        
        cout << "Enter high temperature: ";
        if (!(cin >> monthlyTemps[month][0])) {
            cerr << "Invalid input! Exiting program." << endl;
            return 1;
        }

        cout << "Enter low temperature: ";
        if (!(cin >> monthlyTemps[month][1])) {
            cerr << "Invalid input! Exiting program." << endl;
            return 1;
        }
    }

    // Output phase
    cout << "\n--- Monthly Temperature Summary ---" << endl;
    for (int month = 0; month < 12; ++month) {
        cout << "Month " << month + 1 << ": "
             << "High = " << monthlyTemps[month][0] << "°C, "
             << "Low = " << monthlyTemps[month][1] << "°C" << endl;
    }

    return 0;
}

Quick Note for Python/JS Devs #

Remember: C++ arrays are way more low-level than what you’re used to. There’s no built-in "print all elements" method—you have to handle iteration yourself. Also, array indices start at 0 (just like JS/Python), so months 1-12 map to indices 0-11.

内容的提问来源于stack exchange，提问作者SSBASE