[C++]c++中⼆进制⽂件的创建与使⽤⼆进制⽂件和⽂本⽂件是不同的⽂件类型，因此在创建等⽅式也是不⼀样的
使⽤⽂件⽅式见下表：
"r"（只读）为输⼊打开⼀个⽂本⽂件
"w"（只写）为输出打开⼀个⽂本⽂件
"a"（追加）为追加打开⼀个⽂本⽂件
"rb"（只读）为输⼊打开⼀个⼆进制⽂件
"wb"（只写）为输出打开⼀个⼆进制⽂件
"ab"（追加）为追加打开⼀个⼆进制⽂件
"r+"（读写）为读／写打开⼀个⽂本⽂件
"w+"（读写）为读／写创建⼀个⽂本⽂件
"a+"（读写）为读／写打开⼀个⽂本⽂件
"rb+"（读写）为读／写打开⼀个⼆进制⽂件
"wb+"（读写）为读／写创建⼀个⼆进制⽂件
"ab+"（读写）为读／写打开⼀个⼆进制⽂件
void generateBin(string filename, int npattern ,int ninput, int noutput){
FILE* file;
file = fopen(filename.c_str(), "w");
if (file == NULL)
{
throw runtime_error("network: could not open " + string(filename) + " for writing");
}
fwrite(&npattern, sizeof(int), 1, file);
fwrite(&ninput, sizeof(int), 1, file);
fwrite(&noutput, sizeof(int), 1, file);
float * input = new float[ninput];
float * output = new float[noutput];
float range = 1;
for (int n = 0; n < npattern;n++){
for (int i = 0; i < ninput; i++){
input[i] = range * ((float)rand() / RAND_MAX - 0.5);
}
fwrite(input,sizeof(float),ninput,file);
for (int o = 0; o < noutput; o++){
output[o] = range * ((float)rand() / RAND_MAX - 0.5);
}
fwrite(output, sizeof(float), noutput, file);
}
if (fclose(file) != 0) {
throw runtime_error("network: error on saving to " + string(filename));
}
delete input;
delete output;
}
void readdata(){
int ninput =0;
int noutput = 0;
int npatterns = 0;
size_t data_read = 0;
float* inputs = new float[ninput];
float* targets = new float[noutput];
string filename = "data.bin";
FILE *file = fopen(filename.c_str(), "r");
throw runtime_error("Cannot open file " + filename + " for reading");
int ok =
fread(&npatterns, sizeof(int), 1, file) &&
fread(&ninput, sizeof(int), 1, file) &&
fread(&noutput, sizeof(int), 1, file);
cout << npatterns << " " << ninput << " " << noutput << endl;
cout << "ninput is:" << ninput << endl;
cout << "noutput is:" << noutput << endl;
cout << "npatterns is:" << npatterns << endl;
for (int i = 0; i < npatterns; i++) {
cout << "load_patterns i:" << i << endl;
data_read = fread(inputs, sizeof(float), ninput, file);
cout << "need: " << ninput << " get: " << data_read << endl;
if (data_read != ((size_t)ninput)) {
cout << "Wrong file format " << endl;
fclose(file);
throw runtime_error("Wrong file format");
}
data_read = fread(targets, sizeof(float), noutput, file);
if (data_read != ((size_t)noutput)) {
cout << "Wrong file format " << endl;
fclose(file);
throw runtime_error("Wrong file format");
}
cout << "load_patterns i:" << i << endl;
}
delete inputs;
delete targets;
fclose(file);
}
  上⾯两段程序，试图创建⼀个⼆进制⽂件，并且向其中写⼊data，并且再在其中读出⼆进制数据。但是运⾏的结果是错误的，
data_read 的数量⼩于ninput，原因是因为使⽤了⽂本⽂件的创建⽅式，但是确使⽤了⼆进制⽂件的操作。应该改为如下的代码void generateBin(string filename, int npattern ,int ninput, int noutput){
FILE* file;
file = fopen(filename.c_str(), "wb");
if (file == NULL)
{
throw runtime_error("network: could not open " + string(filename) + " for writing");
}
fwrite(&npattern, sizeof(int), 1, file);
fwrite(&ninput, sizeof(int), 1, file);
fwrite(&noutput, sizeof(int), 1, file);
float * input = new float[ninput];
float * output = new float[noutput];
float range = 1;
for (int n = 0; n < npattern;n++){
for (int i = 0; i < ninput; i++){
input[i] = range * ((float)rand() / RAND_MAX - 0.5);
}
fwrite(input,sizeof(float),ninput,file);
for (int o = 0; o < noutput; o++){
output[o] = range * ((float)rand() / RAND_MAX - 0.5);
}
fwrite(output, sizeof(float), noutput, file);
}
if (fclose(file) != 0) {
throw runtime_error("network: error on saving to " + string(filename));
}
delete input;
delete output;
}
void readdata(){
int ninput =0;
int noutput = 0;
size_t data_read = 0;
float* inputs = new float[ninput];
float* targets = new float[noutput];
string filename = "data.bin";
FILE *file = fopen(filename.c_str(), "rb");
if (file == NULL)
throw runtime_error("Cannot open file " + filename + " for reading"); int ok =
fread(&npatterns, sizeof(int), 1, file) &&
fread(&ninput, sizeof(int), 1, file) &&
fread(&noutput, sizeof(int), 1, file);
fopen 创建文件cout << npatterns << "" << ninput << "" << noutput << endl;
cout << "ninput is:" << ninput << endl;
cout << "noutput is:" << noutput << endl;
cout << "npatterns is:" << npatterns << endl;
for (int i = 0; i < npatterns; i++) {
cout << "load_patterns i:" << i << endl;
data_read = fread(inputs, sizeof(float), ninput, file);
cout << "need: " << ninput << " get: " << data_read << endl;
if (data_read != ((size_t)ninput)) {
cout << "Wrong file format " << endl;
fclose(file);
throw runtime_error("Wrong file format");
}
data_read = fread(targets, sizeof(float), noutput, file);
if (data_read != ((size_t)noutput)) {
cout << "Wrong file format " << endl;
fclose(file);
throw runtime_error("Wrong file format");
}
cout << "load_patterns i:" << i << endl;
}
delete inputs;
delete targets;
fclose(file);
}

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