C++的简单文本IO

从命令行读取一个文件的文件名，输出文本有多少个字符

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>
using namespace std;
int count_words(char *filename){
    int nb_of_chars = 0;
    char ch;
    ifstream inFile;
    inFile.open(filename);
    if(!inFile.is_open()){
        printf("%s cannot open\n", filename);
        exit(EXIT_FAILURE);
    }
    inFile >> noskipws;
    inFile >> ch;
    while(inFile.good()){
        nb_of_chars++;
        inFile >> ch;
    }
    return nb_of_chars;
}
int main(int args, char *argv[]){
    int res;
    res = count_words(argv[1]);
    printf("%s\t%d\n", argv[1], res);
}

要注意的是C++的ifstream创建的inFile会默认跳过空白字符，因此noskipws是一个必要的参数