c - sscanf 直到 c 中的文件末尾

Question

我有一个 C 程序，可以从文本文件创建二进制文件。

/*makeBinry.c*/
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

int main(int argc, char *argv[]){
    char *ptext, *btext="file.bin";
    if(argc != 2){
        printf("Using default \"text.txt\" file to create mnemonics table\n");
        ptext = "text.txt";
    }else{
        ptext = argv[2];
    }

    FILE *fp, *fb;
    if(!(fp=fopen(ptext, "r"))){
        fprintf(stdout, "Error: File %s is not available\n", ptext);
        exit(1);
    }

    if(!(fb = fopen(btext, "wb"))){
        fprintf(stdout, "Error: File %s is cannot be opened to write\n", btext);
        exit(1);
    }

    int i, j, k;
    char s[8], c, stringed[20];

    while(!feof(fp)){
        memset(stringed, '\0', sizeof(stringed));
        fscanf(fp, "%X %d %c %d %[^\n]s", &i, &j, &c, &k, s);
        sprintf(stringed, "%X %d %c %d %[^\n]s", &i, &j, &c, &k, s);
        fwrite(stringed, 1, strlen(stringed), fb);
    }
    fprintf(stdout, "Success: %s file successfully created\n", btext);

    fclose(fp);
    fclose(fb);
    return 0;
}

我有另一个程序，它读取二进制文件中的数据并将其存储到数组中。

/*mainProg.c*/
#include<stdio.h>
#include<stdlib.h>
#include<malloc.h>
#include<string.h>

typedef struct opStruct{
    int hexv, fv, kv;
    char str[8], key;
} node;

node* makeTable(char *filename){
    FILE *fp;
    if(!(fp = fopen(filename, "rb"))){
        fprintf(stdout, "Error: Unable to open file %s\n", filename);
        exit(1);
    }
    int hv, fv, kv;
    char s[8], c, str[20];

    while(!(feof(fp))){
        sscanf(fp,"%X %d %c %d %[^\n]s", &hv, &fv, &c, &kv, str);
        fprintf(stdout, "%X %d %c %d %s", hv, fv, c, kv, str);
    }
    fclose(fp);
    return NULL;
}

int main(){
    int i;
    char *filename = "file.bin";
    node *t_table = makeTable(filename);
    return 0;
}

当我运行mainProg.c时，程序进入无限循环。我认为这是因为 fp 从未增加。如何增加文件指针并仍然使用 sscanf 以格式化方式读取二进制文件？我不允许使用 fread()。由于目前，我没有创建表，因此函数 makeTable 返回 NULL。

此外，由于二进制文件中的行数未知，如何使用 realloc 动态创建数组？

Answer 1

下面的代码

1. 正确处理错误情况
2. 实际上生成一个二进制文件，而不仅仅是另一个文本文件
3. 使用 fscanf() 返回的值，而不是错误的 feof()
4. 使用perror()，因此系统错误消息显示在stderr上
5. 遵循公理:每行只有一个语句，并且每个语句(最多)一个变量声明

可以添加对 fwrite()、fclose() 调用的错误检查，但它们不太可能产生错误

现在是代码

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

    struct record
    {
        unsigned int hv;
        int fv;
        int kv;
        char c;
        char s[8];
    };

int main(int argc, char *argv[])
{
    char *ptext, *btext="file.bin";
    if(argc != 2)
    {
        printf("Using default \"text.txt\" file to create mnemonics table\n");
        ptext = "text.txt";
    }

    else
    {
        ptext = argv[1];
    }

    FILE *fp;
    FILE *fb;

    if(!(fp=fopen(ptext, "r")))
    {
        perror( "fopen for read of text file failed" );
        fprintf(stdout, "Error: File %s is not available\n", ptext);
        exit(1);
    }

    if(!(fb = fopen(btext, "wb")))
    {
        perror( "fopen for write of binary file failed" );
        fprintf(stdout, "Error: File %s is cannot be opened to write\n", btext);
        fclose( fp ); // cleanup
        exit(1);
    }

    struct record myRecord;

    // produce binary file from text input
    // note: leading space in format string, to consume any left over newline, etc
    while(5 == fscanf(fp, " %X %d %c %d %7[^\n]",
                      &myRecord.hv,
                      &myRecord.fv,
                      &myRecord.c,
                      &myRecord.kv,
                      myRecord.s) )
    {
        fwrite( &myRecord, sizeof myRecord, 1, fb );
    }

    fprintf(stdout, "Success: %s file successfully created\n", btext);

    fclose(fp);
    fclose(fb);
    return 0;
}



/*mainProg.c*/
#include <stdio.h>
#include <stdlib.h>
//#include <malloc.h>
#include <string.h>

//typedef struct opStruct
//{
//    int hexv, fv, kv;
//    char str[8], key;
//} node;

struct record
{
    unsigned int hv;
    int fv;
    int kv;
    char c;
    char s[8];
};

//node* makeTable(char *filename)
void makeTable( char *filename )
{
    FILE *fp;
    if(!(fp = fopen(filename, "rb")))
    {
        fprintf(stdout, "Error: Unable to open file %s\n", filename);
        exit(1);
    }

    // implied else, fopen successful

    struct record myRecord;

    // use fscanf() not sscanf()
    while( fread( &myRecord, sizeof myRecord, 1, fp) )
    {
        //sprintf( , "%X %d %c %d %s\n" hv, fv, c, kv, s );
        //fprintf(stdout, "%s", str );
        fprintf( stdout, "\n%X",   myRecord.hv  );
        fprintf( stdout, " %d",    myRecord.fv  );
        fprintf( stdout, " %c",    myRecord.c   );
        fprintf( stdout, " %d",    myRecord.kv  );
        fprintf( stdout, " %8.8s", myRecord.s   );
    }
    fprintf( stdout, "\n" ); // force flush


    fclose(fp);
    //return NULL;
} // end function: makeTable


int main( void )
{
    //int i;
    char *filename = "file.bin";
    //node *t_table = makeTable(filename); // raises compiler warning about unused variable
    makeTable(filename);
    return 0;
} // end function: main