如何将两个已排序的文件合并为一个已排序的文件？

Question

更具体地说，我想将两个排序的整数列表合并到第三个也排序的列表中。我不知道为什么我的代码不起作用！这是一些条目示例和我制作的代码：

文件1：

1
2
3
4
5
6

文件2：

7
8
9
9
9
10

C 代码：

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

void merge(char* arq1, char* arq2){
    FILE* final;
    final = fopen("merge.txt",'w');
    FILE* f1 = fopen(arq1,'rt');
    FILE* f2 = fopen(arq2,'rt');
    if(!f1 || !f2) exit(1);
    // n1 and n2 represents the actual value that's been read. r1 and r2 the status of each file.
    int n1,n2,r1,r2,equal;
    r1 = fscanf(f1,"%d",&n1);
    r2 = fscanf(f2,"%d",&n2);
    while(r1 || r2){
         if((!r1) || (n2 < n1)){
            fprintf(final,"%d ",n2);
            r2 = fscanf(f2,"%d",&n2);
        }else if((!r2) || (n1 < n2)){
            fprintf(final,"%d ",n1);
            r1 = fscanf(f1,"%d",&n1);
        }else{
            equal = n1;
            fprintf(final,"%d ",equal);
            while(n1 == equal) r1 = fscanf(f1,"%d",&n1);
            while(n2 == equal) r2 = fscanf(f2,"%d",&n2);
        }
    }
    fclose(final);
    fclose(f1);
    fclose(f2);
}

int main(int argc, char const *argv[]){
    merge("merge1.txt","merge2.txt"); 

    return 0;
}

算法应该如下工作：

虽然至少其中一个文件仍有内容，但其内容随后将保存在merge.txt 文件中。如果文件 1 和 2 具有相同的内容，我会保存内容并读取这 2 个文件，直到它们找到不同的值，这样合并后的文件就不会有重复的值。

如何将两个排序后的文件合并为一个排序后的文件？

Answer 1

1. fopen() 的模式参数应该是一个字符串。

2. fscanf() 可以在错误或 EOF 时返回 EOF(-1)

3. 失败时，fscanf() 的目标变量的值未定义。

---

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

void merge(char* arq1, char* arq2){
    FILE *final;
    final = fopen("merge.txt", "w"); // <<--(1)
    FILE *f1 = fopen(arq1, "rt"); // <<--(1)
    FILE *f2 = fopen(arq2, "rt"); // <<--(1)
    if(!f1 || !f2 || !final) exit(1); // <<--(1)
    // n1 and n2 represents the actual value that's been read. r1 and r2 the status of each file.
    int n1,n2,r1,r2,equal;

    r1 = fscanf(f1, "%d", &n1);
    r2 = fscanf(f2, "%d", &n2);
    while(r1>0 || r2>0){ // <<--(2)
         if(r1 < 1 || n2 < n1){ // <<--(2)
            fprintf(final, "%d ", n2);
            r2 = fscanf(f2, "%d", &n2);
        }else if(r2 < 1 || n1 < n2){ // <<--(2)
            fprintf(final, "%d ", n1);
            r1 = fscanf(f1, "%d", &n1);
        }else{
            equal = n1;
            fprintf(final, "%d ", equal);
            while(n1 == equal && r1 > 0) r1 = fscanf(f1, "%d", &n1); // <<--(2,3)
            while(n2 == equal && r2 > 0) r2 = fscanf(f2, "%d", &n2); // <<--(2,3)
        }
    }
    fclose(final);
    fclose(f1);
    fclose(f2);
}

int main(int argc, char const *argv[]){
    merge("merge1.txt","merge2.txt"); 

    return 0;
}

Answer 2

OP 发布的代码无法干净编译！

这是编译器的输出：

gcc    -ggdb -Wall -Wextra -Wconversion -pedantic -std=gnu11  -c "untitled.c"  

untitled.c: In function ‘merge’:
untitled.c:6:31: warning: passing argument 2 of ‘fopen’ makes pointer from integer without a cast [-Wint-conversion]
     final = fopen("merge.txt",'w');
                               ^~~

In file included from untitled.c:1:0:
/usr/include/stdio.h:232:14: note: expected ‘const char * restrict’ but argument is of type ‘int’
 extern FILE *fopen (const char *__restrict __filename,
              ^~~~~

untitled.c:7:27: warning: multi-character character constant [-Wmultichar]
     FILE* f1 = fopen(arq1,'rt');
                           ^~~~

untitled.c:7:27: warning: passing argument 2 of ‘fopen’ makes pointer from integer without a cast [-Wint-conversion]

In file included from untitled.c:1:0:
/usr/include/stdio.h:232:14: note: expected ‘const char * restrict’ but argument is of type ‘int’
 extern FILE *fopen (const char *__restrict __filename,
              ^~~~~

untitled.c:8:27: warning: multi-character character constant [-Wmultichar]
     FILE* f2 = fopen(arq2,'rt');
                           ^~~~

untitled.c:8:27: warning: passing argument 2 of ‘fopen’ makes pointer from integer without a cast [-Wint-conversion]

In file included from untitled.c:1:0:
/usr/include/stdio.h:232:14: note: expected ‘const char * restrict’ but argument is of type ‘int’
 extern FILE *fopen (const char *__restrict __filename,
              ^~~~~

untitled.c: In function ‘main’:
untitled.c:33:14: warning: unused parameter ‘argc’ [-Wunused-parameter]
 int main(int argc, char const *argv[]){
              ^~~~

untitled.c:33:32: warning: unused parameter ‘argv’ [-Wunused-parameter]
 int main(int argc, char const *argv[]){
                                ^~~~

关于：

final = fopen("merge.txt",'w');

'mode' 参数必须是字符串。建议在 'mode' 参数周围使用双引号：

final = fopen("merge.txt","w");

关于：

FILE* f1 = fopen(arq1,'rt');

和以前一样，'mode' 参数必须是一个字符串。建议：

FILE* f1 = fopen(arq1,"rt");

main()函数，由于没有用到参数，建议使用签名：

int main( void )

编译时，始终启用警告，然后修复这些警告