如何让 C 程序向文件内容添加行号。例如，“1. #include <stdio.h> 2. #include <stdlib.h>”等等？

Question

#include <stdio.h>
#include <stdlib.h>

int process_stream(FILE *fpntr);
char *fgetline(FILE *fpntr);

int main(int argc, char* argv[]) {

    FILE *fpntr;
    char filename[100], c;
    int a = 0;

    printf("Please enter a file name/directory: \n");
    scanf("%s", filename);

    fpntr = fopen(filename, "r");
    if (fpntr == NULL) {
        printf("cannot open file \n");
        exit(0);
    }

    //read contents from file
    c = fgetc(fpntr);
    while (c != EOF){

        printf ("%c", c);
        c = fgetc(fpntr);
        if (c == '\n')

            {
                a++;
                printf("%d", a);
    }}

    fclose(fpntr);
    return 0;
    exit (0);
}

Answer 1

首先按照你说的去做

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char* argv[]) {

    FILE *fptr;
    char filename[100];
    int c;
    int lineNumber = 1;

    printf("Please enter a file name/directory: \n");
    scanf("%99s", filename);

    // Open the file
    fptr = fopen(filename, "r");
    if (fptr == NULL) {
        printf("cannot open file \n");
        exit(0);
    }

    //read contents from file
    // While ((c = read a character) is not EOF)
    while ((c = fgetc(fptr)) != EOF){
        // If (c is \n)
        if (c == '\n') {
            // Print "lineNumber", then increment it
            printf("%d. ", lineNumber);
            lineNumber++;
        }
        // Print c
        printf ("%c", c);
    // End while
    }

    // Close the file
    fclose(fptr);
    return 0;
}

不幸的是，此代码无法正常运行，其输出为

#include <stdio.h>1. 
#include <stdlib.h>2. 
int hoge;3. 
int fuga;4.

当输入文件是

#include <stdio.h>
#include <stdlib.h>
int hoge;
int fuga;

错误是您在行尾打印行号。它们应该在行的开头。我会使用一个标志来指示行的开头。

#include <stdio.h>
#include <stdlib.h>

int main(int argc, char* argv[]) {

    FILE *fptr;
    char filename[100];
    int c;
    int lineNumber = 1;
    int isBeginningOfLine = 1;

    printf("Please enter a file name/directory: \n");
    scanf("%99s", filename);

    fptr = fopen(filename, "r");
    if (fptr == NULL) {
        printf("cannot open file \n");
        exit(0);
    }

    //read contents from file
    while ((c = fgetc(fptr)) != EOF){
        if (isBeginningOfLine) {
            print("%d. ", lineNumber);
            isBeginningOfLine = 0;
        }
        if (c == '\n') {
            lineNumber++;
            isBeginningOfLine = 1;
        }
        printf ("%c", c);
    }

    fclose(fptr);
    return 0;
}

现在我得到了

1. #include <stdio.h>
2. #include <stdlib.h>
3. int hoge;
4. int fuga;

如何让 C 程序向文件内容添加行号。例如，“1. #include <stdio.h> 2. #include <stdlib.h>”等等？

How can you make a C program add line numbers to a file's contents. E.g., "1. #include <stdio.h> 2. #include <stdlib.h>", etc.?

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