How to overcome Memory error when reading large file (over 1GB) -- C/C++

I am trying to read a file of over 1GB (which has 1,157,421,364 bytes), it gives memory error when using fread() function, but works well when I use fgets() function. Note: I have intermixed C and C++..

Can someone help me to overcome this memory error, am I doing something wrong?

Thanks in advance...

Error is "Memory Error"

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cerrno>
#include <cstring>

void read_file2(FILE* readFilePtr){
    long file_size;

    fseek(readFilePtr, 0L, SEEK_END);
    file_size = ftell(readFilePtr);
    rewind(readFilePtr);

    char *buffer;
    buffer = (char*) malloc (sizeof(char)*file_size);
    if (buffer == NULL) {
        fputs("Memory Error", stderr);
        exit(2);
    }
    long lines = 0;
    if (fread(buffer, 1, file_size, readFilePtr) != file_size){
        fputs("Reading Error", stderr);
        exit(1);
    }
    char *p = buffer;
    while (p = (char*) memchr(p, '\n', (buffer + file_size) - p)){
        ++p;
        ++lines;
    }
    printf("Num of lines %ld\n", lines);
    free(buffer);
}

int main(int argc, char** argv){
    clock_t begin_time, end_time;
    float time_consumed;

    begin_time = clock();

    FILE* inputFilePtr = fopen(argv[1], "rb");

    if(inputFilePtr == NULL){
        printf("Error Opening %s: %s (%u)\n", argv[1], strerror(errno), errno);
        return 1;
    }

    read_file2(inputFilePtr);

    end_time = clock();

    time_consumed = ((float)end_time - (float)begin_time)/CLOCKS开发者_StackOverflow_PER_SEC;
    printf("Time consumed is -- %f\n", time_consumed);
    return 0;
}

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You can read the file in chunks, instead of reading it as a whole, reading all of the file to one allocated buffer means a huge memory allocation of your application, do you really want that?. That's being said assuming you don't need to process it all in once (which is true in most cases).

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You usually don't read big files in one go like that. You use something called buffered reads. Essentially you continuously call fread in a loop until there's nothing left to read.