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c++里怎样读文件呀,是这样的一个文件,每行行有两个数据,共有n行,要分别把每行的第一,二个元素读取出来,分别存到a,b两个向量当中,不知道该怎么处理。 -6.0000000e+001 2.6356764e+000 -5.9899487e+001 2.6289755e+000 -5.9798974e+001 2.6222747e+000 -5.9698462e+001 2.6155738e+000 -5.9597949e+001 2.6088730e+000 -5.9497436e+001 2.6021721e+000 -5.9396923e+001 2.5954713e+000 -5.9296411e+001 2.5887704e+000 -5.9195898e+001 2.5820696e+000 -5.9095385e+001 2.5753687e+000 -5.8994872e+001 2.5686679e+000 -5.8894359e+001 2.5619670e+000 -5.8793847e+001 2.5552662e+000 -5.8693334e+001 2.5485653e+000 -5.8592821e+001 2.5418645e+000 -5.8492308e+001 2.5351636e+000 -5.8391796e+001 2.5284627e+000 -5.8291283e+001 2.5217619e+000 -5.8190770e+001 2.5150610e+000 -5.8090257e+001 2.5083602e+000 -5.7989744e+001 2.5016593e+000 -5.7889232e+001 2.4949585e+000 -5.7788719e+001 2.4882576e+000 -5.7688206e+001 2.4815568e+000 -5.7587693e+001 2.4748559e+000 -5.7487181e+001 2.4681551e+000解答如下: #include<iostream> #include<fstream> #include<sstream>#include<string>#include<vector>using namespace std;int main(){ ifstream infile("d://aaa.txt"); //默认是输出模式,附加模式(即不破坏原有内容)则: ofstream outfile ("d://bbb.txt",ios_base::app) ofstream outfile("d://bbb.txt"); string sline;//每一行 string s1,s2; vector<string> vec1,vec2; while(getline(infile,sline)) { istringstream sin(sline); sin>>s1>>s2; vec1.push_back(s1); vec2.push_back(s2); } outfile<<"第1列:"<<endl; vector<string>::const_iterator it; for(it=vec1.begin();it!=vec1.end();++it) outfile<<*it<<"/n"; outfile<<"第2列:"<<endl; for(it=vec2.begin();it!=vec2.end();++it) outfile<<*it<<"/n"; outfile<<endl; return 0;}+++++++++++++++++++++华丽的分割线+++++++++++++++++++++++第二个示例#include<stdio.h> int main() { char str[80]; char get[10]; int i; FILE *fp,*fget; fp=fopen("D://1.txt","a+"); scanf("%s",str); fprintf(fp,"%s",str); fseek(fp,0,SEEK_SET);//函数的第一个参数的要操作的文件指针 //第三个参数是你的偏置量的参考基点(可以是文件头/文件尾/当前位置) //第二个参数是你的偏置量 fscanf(fp,"%s",get); fget=fopen("D://2.txt","w"); fprintf(fget,"%s",get); printf("%s",get); getchar(); getchar(); }+++++++++++++++++++++++++++华丽的分割线++++++++++++++++++++++++示例三: #include <iostream.h> #include <fstream.h> void main() { ifstream fin; char st[10]; fin.open("input.txt", ios::in|ios::nocreate); // 以输入方式打开文件,如果文件不存在,不会创建文件 fin.getline(st, 10, '/n'); // 10为字符串数组最大可用空间,包括作结束标记的0; '/n'为输入的结束字符 cout<<st<<endl; } 上面关于可以指代文件的结束点,恩值得注意一下,没有测试过 |
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