# va-arg

**Repository Path**: functioner/va-arg

## Basic Information

- **Project Name**: va-arg
- **Description**: No description available
- **Primary Language**: C
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2022-05-13
- **Last Updated**: 2022-05-13

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# va-arg
In this exercise, you are suppoosed to implement a variable-length arguments function like printf, but calculate the sum instead.
We have provide you the skeleton in main.cc and vasum.cc, your job is to finish function VaSum in vasum.cc.

Function 
```
double VaSum(const char *fmt, ...) 
```
will receive a format string in the first arg, this string will tell VaSum how to parse the following args.
For example, if the fmt is "%d, %f, %s", there will be three arguments and the type will be int, double and char*.

You should parse the three arguments respectively according to fmt, **you don't need to worry about any wrong arguments, we assume all the arguments are correct in this exercise**.<br/>

You can refer to this classical programs to finish the procedure of handling fmt, which is also show in class:
```
void minprintf(char *fmt,...)
{
    va_list ap; /* points to each unnamed arg in turn */
    char *p,*sval;
    int ival;
    double dval;

    va_start(ap,fmt);   /* make ap point to 1st unnamed arg */
    
    for(p=fmt;*p;p++)
    {
        if(*p != '%')
        {
            putchar(*p);
            continue;
        }

        switch(*++p)
        {
            case 'd':
                ival = va_arg(ap,int);
                printf("%d",ival);
                break;
            case 'f':
                dval = va_arg(ap,double);
                printf("%f",dval);
                break;
            case 's':
                for(sval = va_arg(ap,char *);*sval;sval++)
                    putchar(*sval);
                break;
            default:
                putchar(*p);
                break;
        }
    }
    va_end(ap); /* clean up when done */
}
```