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