关于python中readlines函数的参数hint的相关知识总结

>>> fr=open('readme.txt')
>>> help(fr.readlines)
Help on built-in function readlines:
 
readlines(hint=-1, /) method of _io.TextIOWrapper instance
    Return a list of lines from the stream.
    
    hint can be specified to control the number of lines read: no more
    lines will be read if the total size (in bytes/characters) of all
    lines so far exceeds hint.

>>> f=open('readme.txt')
>>> f.readlines()
['1\n', '22\n', '\n', '333']

def readlinesFile(filename,nbyte):
    '''
    探索f.readlines(i)中i的作用，典型的调用形式：
    readlinesFile('readme.txt',12)
    '''
    for i in range(nbyte):
        f=open(filename)
        ss=f.readlines(i)                       
        if i==0:#如果hint=0，先把每一个元素输出                
            textline=len(ss)#文件的总行数
            ntotalbyte=0#文件的总字数
            nwritebyte=0#已经写了的字节数
            for j in range(textline):
                #nwritebyte=ntotalbyte#已经写了的字节数
                ntotalbyte=ntotalbyte+len(ss[j])
                rowbyte=0#已经写了的新行的字节数，用来记一行已经输出的字节个数
                while nwritebyte<ntotalbyte:#当已写字节<总字节数
                    print(f'{nwritebyte+1}:',repr(ss[j][rowbyte])) #repr是为了输出换行符
                    nwritebyte=nwritebyte+1
                    rowbyte=rowbyte+1
            print(f'行数={textline},字数={ntotalbyte}')
        print(f'f.readlines{i}={ss}') 
        f.close()

def readlinesFile(filename,nbyte):
    '''
    探索f.readlines(i)中i是指什么，典型的调用形式：
    readlinesFile('readme.txt',12)
    '''
    specialByte=[]#存储特殊的字节数用
    for i in range(nbyte):
        with open(filename) as f:#使用with语句就可以不使用f.close()了
            ss=f.readlines(i)                       
            if(i==0):#如果hint=0，先把每一个元素输出
                print(ss)
                textline=len(ss)#文件的总行数
                ntotalbyte=0#文件的总字数
                nwritebyte=0#已经写了的字节数
                for j in range(textline):
                    #nwritebyte=ntotalbyte#已经写了的字节数
                    ntotalbyte=ntotalbyte+len(ss[j])
                    rowbyte=0#已经写了的新行的字节数，用来记一行已经输出的字节个数
                    while nwritebyte<ntotalbyte:#当已写字节<总字节数
                        if(nwritebyte is ntotalbyte-1):
                            specialByte.append(nwritebyte)
                            print(f'\033[0;31;47m{nwritebyte+1:2d}:',repr(ss[j][rowbyte]),'\033[0m')#\033[0m是字体和背景颜色设置，注意可能需要其他库的支持
                        else:
                            print(f'{nwritebyte+1:2d}:',repr(ss[j][rowbyte])) 
                        nwritebyte=nwritebyte+1     
                        rowbyte=rowbyte+1
                print(f'\033[0;31;40m行数={textline:2d},字数={ntotalbyte:2d}\033[0m')
            if i in specialByte:
                print(f'\033[0;31;47mf.readlines{i:<2d}={ss}\033[0m') #<是左对齐
            else:
                print(f'f.readlines{i:<2d}={ss}') #<是左对齐