一个objective-c程序及main函数之参数

#import<Foundation/Foundation.h>

int main(int argc, char *argv[])
{
    if (argc == 1)
    {
        NSLog(@"you need to provide a file name");
        return 1;
    }

    FILE* file = fopen(argv[1], "r");
    char words[100];
    while (fgets(words, 100, file))
    {
        words[strlen(words) - 1] = '\0';
        NSLog(@"%s is %d character long", words, strlen(words));
    }

    fclose(file);

    return 0;
}

argc是参数个数，argv是参数值：

例如上述程序在终端下运行时输入：

./main.exe words.txt

若argc==1表示只输入了./main.exe，缺乏文件名。

argv[0]中存程序名字(./main.exe);

argv[1]中存文件名(words.txt).