#include <stdio.h>

int main(int argc, char** argv) {
  FILE *input, *output;
  int format, N, M, i, j;

  if(argc != 6 || (strcmp(argv[3], "d") && strcmp(argv[3], "f"))) {
    fprintf(stderr, "Usage: %s eingang.dat ausgang.dat [d|f] N M\n", argv[0]);
    return 1;
  }

  if((input = fopen(argv[1], "r")) == NULL) {
    fprintf(stderr, "Cannot open input file.\n");
    goto error_input;
  }

  if((output = fopen(argv[2], "w")) == NULL) {
    fprintf(stderr, "Cannot open output file.\n");
    goto error_output;
  }

  format = strcmp(argv[3], "d"); /* 0 is double, 1 is float */
  N = atoi(argv[4]), M = atoi(argv[5]);

  if(format == 0) {
    double* data = (double*) malloc(sizeof(double) * M * N);
    fread(data, sizeof(double), M * N, input);

    for(i = 0; i < M; i++) {
      for(j = 0; j < N; j++) {
        fprintf(output, "%f", data[j + i * N]);
        fprintf(output, (j == N - 1) ? "\n" : "\t");
      }
    }
  } else {
    float* data = (float*) malloc(sizeof(float) * M * N);
    fread(data, sizeof(float), M * N, input);

    for(i = 0; i < M; i++) {
      for(j = 0; j < N; j++) {
        fprintf(output, "%f", data[j + i * N]);
        fprintf(output, (j == N - 1) ? "\n" : "\t");
      }
    }
  }

  fclose(output);
error_output:
  fclose(input);
error_input:

  return 0;
}