[英]Reading text files with strtol in C line by line
OK so I've got this function which finds the average of all numbers in a file: 好的,所以我有了此函数,该函数可以查找文件中所有数字的平均值:
float averageOfNumbers(FILE *fp_in)
{
int n=0,S=0;
char red[1024];char *ptr;
int p_a_h;
float sr;
while(!feof(fp_in)){
if(fgets(red,1024,fp_in)!=NULL){
ptr =red;
while(p_a_h = strtol(ptr, &ptr, 10)){
if((p_a_h>0&&S>INT_MAX-p_a_h)||(p_a_h<0&&S<INT_MIN-p_a_h)){
printf("OVERFLOW\n");
break;
}
else{
S=p_a_h+S;
n++;}
}
}
}
sr=S/n;
return sr;
}
It works fine when there are only numbers in the file but if it finds anything other than a digit, the program will crash. 当文件中只有数字时,它可以正常工作,但是,如果找到的不是数字,则程序将崩溃。 How can I make it so that the program ignores other symbols.
如何使程序忽略其他符号。 For example here is a text file:
例如,这是一个文本文件:
wdadwa 321 1231 das 421124 1 wdasdad 4 1412515
sad14312 yitiyt453534 3554312 sad -2 -53 -12 -231 #@!
#!312 -2 241 -46343 sada 21312 65454
Average should be: 310422 平均值应为:310422
Add an additional check in the if
condition. 在
if
条件中添加其他检查。
p_a_h==0 && (strlen(ptr)>1 || (strlen(ptr)==1 && ptr[0]!='0'))
I am making use of the fact that strtol
returns 0L
if the conversion is invalid(if the string contains non-digit characters). 我利用以下事实:如果转换无效(如果字符串包含非数字字符),
strtol
返回0L
。 But checking for this alone, also skips if the actual string contains 0
. 但是,仅检查这一点,如果实际字符串包含
0
,也会跳过。 I leave the rest to understand it yourself. 我让其余的人自己了解它。
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