C语言实现连续重复行过滤：字符数组方案技术问询

Alright, let's get your C program for filtering consecutive duplicate lines up and running. You’ve already laid the groundwork with your two character arrays and started the line-reading loop—here’s how to flesh out the rest of the logic correctly:

First, let's start with the complete code, then break down the key parts:

#include <stdio.h>
#include <string.h>

#define MAXCHARS 79  // As specified in your project

int main() {
    char newArray[MAXCHARS];
    char oldArray[MAXCHARS] = "";  // Initialize to empty for first line comparison
    int i;
    int newCh;

    while (1) {
        // Read each line into newArray (your loop, completed)
        for (i = 0; i < MAXCHARS - 1; i++) {  // Leave space for null terminator
            newCh = getchar();
            
            // Stop at newline or end of file
            if (newCh == '\n' || newCh == EOF) {
                break;
            }
            newArray[i] = newCh;
        }
        // Null-terminate the array to make it a valid C string
        newArray[i] = '\0';

        // Exit loop if we hit EOF with no characters read
        if (newCh == EOF && i == 0) {
            break;
        }

        // Compare current line with the previous one
        if (strcmp(newArray, oldArray) != 0) {
            // Print the line only if it's not a duplicate
            printf("%s\n", newArray);
            // Update oldArray to the current line for next iteration
            strncpy(oldArray, newArray, MAXCHARS);
            oldArray[MAXCHARS - 1] = '\0';  // Ensure null termination even if array is full
        }
    }

    return 0;
}

• Null Termination: This is non-negotiable in C! We add '\0' to newArray after reading characters because functions like strcmp and printf rely on null-terminated strings to work correctly.
• Buffer Overflow Prevention: We use MAXCHARS - 1 in the for loop to reserve one spot for the null terminator—this stops us from writing past the end of the array.
• Initialization: oldArray starts as an empty string so the first line will always be printed (since it can’t match an empty string).
• EOF Handling: We check if we hit EOF without reading any characters to exit the loop cleanly, avoiding infinite loops or extra empty lines.
• String Comparison: strcmp does the heavy lifting here—if it returns a non-zero value, the lines are different, so we print the current line and update oldArray.

This program will read input (from stdin or a redirected file) and only output each line if it’s not identical to the line immediately before it, exactly what you need for filtering consecutive duplicates.

内容的提问来源于stack exchange，提问作者z.rubi