Question

我试图在txt文件中保留一个conter，我编写了一个函数，当我调用函数时，函数应该读取txt之后，它应该递增并写入文件。

在我的txt（＆＃34; test.txt＆＃34;）中只有一个字符。它是＆＃34; 0＆＃34;。

代码在这里：

void readAndwrite(){

    int total = 23;
    FILE *fread, *fwrite;
    fread = fopen("test.txt", "r");
    fwrite = fopen("test.txt","w");
    fscanf(fread,"%d",&total);
    fclose(fread);
    ++total;

    fprintf(fwrite ,"%d",total);
    fclose(fwrite);



}

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


    readAndwrite();
    readAndwrite();
    readAndwrite();
    readAndwrite();
    readAndwrite();
    readAndwrite();


    return 0;
}

为什么这不起作用？

Answer 1

你可以打开两次但不能同时打开，因为“w”标志会破坏内容，所以：

void readAndwrite(){    
    int total = 23;
    FILE *f;
    f = fopen("test.txt", "r");
    if(!f) {
        perror("File opening failed");
    }
    else{
        fscanf(f,"%d",&total);
        fclose(f);
        printf("%d\n", total);
        ++total;
        f = fopen("test.txt","w");
        fprintf(f ,"%d",total);
        fclose(f);
    }
}

如果您想同时读/写，请查看doc和“w +”标记

将计数器保存在txt文件中

1 个答案: