This is the code which read a matrix 10x10 from a file "F1.txt"
#include <stdio.h>
int main( int argc, char ** argv ) {
FILE * fr;
fr = fopen("F1.txt","r");
int i, j;
int matrix[10][10] = {0.0};
for(i = 0; i < 10; i++)
{
for(j = 0; j < 10; j++)
{
fscanf(fr, "%d",&matrix[i][j]);
printf("%d\n", matrix[i][j]);
}
}
getchar();
return 0;
}
"F1.txt" looks like this:
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 4 34 56 43 32 124 52 212 3
32 343 34 544 43 32 7 52 456 98
It works without problems but the output is:
12
343
34
544
43
32
124
52
212
3
12
343
34
544
43
32
124
52
212
..........
etc....
I have to detect the end of line to make my input the same like in F1.txt
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 343 34 544 43 32 124 52 212 3
12 4 34 56 43 32 124 52 212 3
32 343 34 544 43 32 7 52 456 98
.
Rewrite the loops the following way
for(i = 0; i < 10; i++)
{
for(j = 0; j < 10; j++)
{
fscanf(fr, "%d",&matrix[i][j]);
printf("%3d ", matrix[i][j]);
}
printf( "\n" );
}
You are reading the data correctly, but you are not printing it right. Your program inserts '\n' after each character, that's why you see so many lines.
Change your program like this to see the output that you expect:
for(i = 0; i < 10; i++)
{
for(j = 0; j < 10; j++)
{
fscanf(fr, "%d",&matrix[i][j]);
printf("%d ", matrix[i][j]); // <<== Replace \n with a single space
}
printf("\n"); // <<== Add this line
}
Or if you just want your input formatted, you can write your end of line in the outer loop on i.
for(i = 0; i < 10; i++)
{
for(j = 0; j < 10; j++)
{
fscanf(fr, "%d",&matrix[i][j]);
printf("%d\t", matrix[i][j]);
}
printf("\n");
}
For your knowledge, EOL is usually a LF character or combination of CR-LF characters. In C they are represented by \n or \r\n respectively.
A possible solution is that you can use fgets to read a complete line at once (fgets will read one line only by itself). Then read out the integers from that string using sscanf or strtok.
I suggest you to use sscanf if you know number of integers in every line.
Otherwise, if a line can contain any amount of numbers then you can use strtok with " " (space) as the delimitter.
You can read more about these functions here: sscanf , strtok
fscanf(fr, "%d",&matrix[i][j]);
printf("%d", matrix[i][j]);
if(j < 10-1)
printf(" ");
else
printf("\n");
Related
I am able to print out a 2D array into an output file but it is not uniform. I would like to have the 2D array evenly spaced when it is printed out. I am fairly new at programing in C so any help would be greatly appreciated!
My Code:
#include <stdio.h>
#include <stdlib.h>
/**
* Driver method for program
*/
int main()
{
int nums[200];
int i = 0;
int j = 0;
FILE * in_file;
FILE * out_file;
srand(time(0)); //seed for random generator
/**
* if loop reads text file and stores numbers into array
*/
if (in_file = fopen("Data.txt", "r")) {
while (fscanf(in_file, "%d", &nums[i]) != EOF) {
i++;
}
int numbsinfile = i;
int random = randomNumber(2, 12);
int matrix1[5][random];
int matrix2[random][5];
out_file = fopen("out.txt", "w");
fprintf(out_file, "Matrix 1: \n");
fprintf(out_file, "Rows = 5 \n");
fprintf(out_file, "Columns = %d \n\n", random);
for(i = 0; i < 5; i++ ){
for(j = 0; j < random; j++){
int rand = randomNumber(0, numbsinfile);
matrix1[i][j] = nums[rand];
fprintf(out_file, "%d \t\t", matrix1[i][j]);
}
fprintf(out_file, "\n");
}
fclose(in_file);
fclose(out_file);
}
return 0;
}
/**
* Generates and prints random
* numbers in range [lower, upper].
*/
int randomNumber(int lower, int upper) {
int num = (rand() % (upper - lower + 1)) + lower;
return num;
}
The input file I am using along with the output file that my code produces. I am basically just wanting to clean up the 2D array that is printed to the output file.
input file:
23 34 -54 21 45 34 65 -54 21 45 34 65 -34 24 58
49 45 10 -57 20
57 39 20 58 23 10 20 58 -60 76 -82 28
28 -37 49 358 47 -50 37 29
57 -29 -20 47 69
93 57 23 49 -38 49 27 -40 48 39
56 -30 47 28 49
37 49
27 26 10 20 58 -60 26 10 20 58 -60 76 -82 28
28 -37 49 -28 93 28
73 47 27 83 37 -29 40 37 49 20
17 -26 12 17 17
18 38 29 39 -118
19 10 20 58 -60 76 -82 28
28 -37 49 59 10 58 -60 76 -82 28
28 -37 49 59 10 20 58 -60 76 -82 28
28 -37 49 30 -58 58 38 49 30 -58 58 38
49 30 -58 58 38
28 39
39 48 23 -50 28
48 29 39 40 29
My output file:
Matrix 1:
Rows = 5
Columns = 12
28 39 20 49 58 76 37 -26 47 -40 216309856 26
57 -50 30 47 29 58 73 20 26 216309856 49 26
216309856 30 59 45 20 23 -50 83 -50 -37 28 30
10 10 23 28 47 45 34 10 19 -38 -118 28
47 49 -40 20 49 29 10 20 58 69 10 28
How to print a “neat” 2D array in C (?)
Find the longest text width using snprintf(NULL, 0, some_format, ...
int width = 1;
for(i = 0; i < 5; i++ ) {
for(j = 0; j < random; j++) {
int rand = randomNumber(0, numbsinfile);
matrix1[i][j] = nums[rand];
int w = snprintf(NULL, 0, "%d", matrix1[i][j]);
if (w > width) width = w;
}
}
Use * in the specifier and width for printing.
for(i = 0; i < 5; i++ ) {
for(j = 0; j < random; j++) {
fprintf(out_file, " %*d", width, matrix1[i][j]);
}
fprintf(out_file, "\n");
}
What's wrong with this code?
My task is: Create a square matrix of integers with a size of 9x9. Fill the matrix with random numbers. Display the main and side diagonal symmetrically with respect to the vertical axis. The example of expected result is here: matrix
Matrix :
20 20 76 65 93 76 16 2 85
6 87 78 43 48 81 71 90 38
10 12 35 77 48 88 24 53 7
12 66 51 35 74 7 30 22 49
58 14 71 46 68 68 10 81 51
98 16 74 47 64 25 17 30 37
2 44 44 74 34 54 86 73 28
85 4 57 75 18 28 51 76 2
35 17 53 76 15 91 83 85 72
The main and side diagonal:
85 20 76 65 93 76 16 2 20
6 90 78 43 48 81 71 87 38
10 12 24 77 48 88 35 53 7
12 66 51 7 74 35 30 22 49
58 14 71 46 68 68 10 81 51
98 16 74 25 64 47 17 30 37
2 44 86 74 34 54 44 73 28
85 76 57 75 18 29 51 4 2
72 17 53 76 15 91 83 85 35
But in fact the program prints only the main matrix with random numbers and after that stops.
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <Windows.h>
int main()
{
int a = 9;
int matrix[a][a];
int temp;
int i, j, n;
srand((unsigned)time(NULL));
printf("Matrix : \n\n");
for (i = 0; i < a; ++i) {
for (j = 0; j < a; ++j) {
matrix[i][j] = rand() % 100;
printf("%d\t", matrix[i][j]);
}
printf("\n\n");
}
printf("The main and side diagonal:\n\n");
for (i = 0; i < a; ++i) {
temp = matrix[i][i];
matrix[i][i] = matrix[i][(a - 1) - i];
matrix[i][(a - 1) - i] = temp;
}
for (i = 0; i < a; ++i) {
for (j = 0; j < a; ++j) {
printf("Result:", matrix[i][j]);
printf("\n\n\n");
system("pause");
return 0;
}
}
}
You are returning where you are not supposed to. (in middle of the calculation). You should return after you end up working on the for loops.
for (i = 0; i < a; ++i) {
for (j = 0; j < a; ++j) {
printf("Result:", matrix[i][j]); <--- Not printing element
printf("\n\n\n");
system("pause");
return 0; <-----
}
}
It should be
for (i = 0; i < a; ++i) {
for (j = 0; j < a; ++j) {
printf("Result: %d ", matrix[i][j]); <----You forgot the
//format specifier
printf("\n\n\n");
system("pause");
}
}
return 0;<-----
Readability is hampered when the indentation is like this. You implemented wrong logic out of it.
OP asks that it stops after printing "Result" that is because you forgot to put the format specifier in the code. That's why none of the element is printed.
Op wants to print the main and side diagonal symmetrically with respect to the vertical axis.
Now this is everything to with the print part.
Now we have to find a way that will let us distinguish which one is diagonal element and which one is not.
Suprisingly the answer should be known to someone who is writing the previous swapping logic. (Though it is not clear why OP swapped it).
Now all element matrix[p][q] will be from either diagonal if p=q or p+q=a-1. (Note that matrix is a square matrix).
But OP meant to print the matrix
for (i = 0; i < a; ++i) {
if( i == 0) printf("The main and side diagonal : \n");
for (j = 0; j < a; ++j) {
printf("%d\t", matrix[i][j]);
}
printf("\n");
}
}
Use functions. You print the matrix twice; you should have a function to print the matrix which you call twice.
With such a function, you'd not make the mistakes in the tail end of your code. For example, you could use this:
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
static void print_matrix(const char *tag, int size, int matrix[size][size])
{
printf("%s (%dx%d):\n\n", tag, size, size);
for (int i = 0; i < size; ++i)
{
const char *pad = "";
for (int j = 0; j < size; ++j)
{
printf("%s%-2d", pad, matrix[i][j]);
pad = " ";
}
printf("\n\n");
}
}
int main(int argc, char **argv)
{
unsigned seed = time(0);
int a = 9;
int matrix[a][a];
if (argc == 2)
seed = atoi(argv[1]);
srand(seed);
printf("Seed: %u\n", seed);
for (int i = 0; i < a; ++i)
{
for (int j = 0; j < a; ++j)
matrix[i][j] = rand() % 100;
}
print_matrix("Matrix", a, matrix);
for (int i = 0, j = a - 1; i < a; ++i, --j)
{
int temp = matrix[i][i];
matrix[i][i] = matrix[i][j];
matrix[i][j] = temp;
}
print_matrix("The main and side diagonal", a, matrix);
return 0;
}
The code reports the seed it uses; that allows you to reproduce any run by specifying the seed to use as a command line argument.
Example output:
Seed: 1511470282
Matrix (9x9):
11 39 3 88 98 63 75 81 76
93 9 60 22 45 50 46 58 65
13 99 25 43 14 57 44 70 65
30 57 55 0 37 84 47 49 40
60 28 46 1 96 78 33 20 9
93 61 11 38 84 16 91 26 15
43 85 66 72 85 39 96 45 45
45 25 33 3 78 90 61 65 62
88 84 56 34 74 8 78 57 74
The main and side diagonal (9x9):
76 39 3 88 98 63 75 81 11
93 58 60 22 45 50 46 9 65
13 99 44 43 14 57 25 70 65
30 57 55 84 37 0 47 49 40
60 28 46 1 96 78 33 20 9
93 61 11 16 84 38 91 26 15
43 85 96 72 85 39 66 45 45
45 65 33 3 78 90 61 25 62
74 84 56 34 74 8 78 57 88
The swapping process, in case it isn't obvious, swaps the first and last elements of the first row, the second and last but one element in the second row, and so on, forming an X of swapped elements.
I want to generate a series of "random" unique numbers, for use at a card game! These numbers should be between 0 and 81.
I don't care about security or speed at this stage, i just want something simple to have the work done.
In my code below, i have managed to create 2 unique random numbers in the array that holds them, but the rest 10 numbers don't change but stay -1 that was the initial value..
I have found more accurate ways for random number generation, but i will check them out at a later stage!
#include <stdio.h>
#include <stdlib.h>
int getRandomNumber(int Min, int Max)
{
double rnd= (double)rand()/((double)RAND_MAX+1);
return (int)(rnd*(Max-Min+1))+Min;
}
int main()
{
int j,counter,temp,deck[13];
srand(time(NULL));
int i;
counter=1;
for (i=0;i<12;i++)
{deck[i]=-1;
temp = getRandomNumber(0,81);
for (j=0;j<=i;j++)
{if (temp==deck[j])
{counter=0;}
if (counter!=0)
deck[i]=temp;
}
}
for(i=0;i<12;i++)
printf("%d ",deck[i]);
}
Your code has one of the weirder indentation and brace layout schemes I've ever seen:
#include <stdio.h>
#include <stdlib.h>
int getRandomNumber(int Min, int Max)
{
double rnd= (double)rand()/((double)RAND_MAX+1);
return (int)(rnd*(Max-Min+1))+Min;
}
int main()
{
int j,counter,temp,deck[13];
srand(time(NULL));
int i;
counter=1;
for (i=0;i<12;i++)
{deck[i]=-1;
temp = getRandomNumber(0,81);
for (j=0;j<=i;j++)
{if (temp==deck[j])
{counter=0;}
if (counter!=0)
deck[i]=temp;
}
}
for(i=0;i<12;i++)
printf("%d ",deck[i]);
}
Converted to a more orthodox style (Allman, more or less — see Wikipedia on Indent style), you get:
#include <stdio.h>
#include <stdlib.h>
static int getRandomNumber(int Min, int Max)
{
double rnd = (double)rand() / ((double)RAND_MAX + 1);
return (int)(rnd * (Max - Min + 1)) + Min;
}
int main(void)
{
int j, counter, temp, deck[13];
srand(time(NULL));
int i;
counter = 1;
for (i = 0; i < 12; i++)
{
deck[i] = -1;
temp = getRandomNumber(0, 81);
for (j = 0; j <= i; j++)
{
if (temp == deck[j])
{
counter = 0;
}
if (counter != 0)
deck[i] = temp;
}
}
for (i = 0; i < 12; i++)
printf("%d ", deck[i]);
}
The static and int main(void) are needed to get the code past my default compilation options; otherwise, they're cosmetic.
Now we can see some problems. The counter is set to 1 once, outside the outer loop; it is set to 0 sometimes inside the loop, but once that happens, it is never reset to 1, so no further numbers are added to the deck. You need to rework the inner loop, maybe like this:
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
static int getRandomNumber(int Min, int Max)
{
double rnd = (double)rand() / ((double)RAND_MAX + 1);
return (int)(rnd * (Max - Min + 1)) + Min;
}
int main(void)
{
int deck[13];
srand(time(NULL));
for (int i = 0; i < 12; i++)
{
int temp = getRandomNumber(0, 81);
deck[i] = -1;
int counter = 1;
for (int j = 0; j <= i; j++)
{
if (temp == deck[j])
{
counter = 0;
break;
}
}
if (counter != 0)
deck[i] = temp;
else
i--; // Try again with a new random choice for the same i
}
const char *pad = "";
for (int i = 0; i < 12; i++)
{
printf("%s%d", pad, deck[i]);
pad = " ";
}
putchar('\n');
return 0;
}
I dislike trailing blanks, so the printing loop takes care to ensure there aren't any.
Sample output with getRandomNumber() — on macOS Sierra 10.12.2 with GCC 6.3.0:
7 73 38 61 11 13 41 66 29 39 72 20
7 2 18 17 54 31 45 40 34 22 63 16
7 13 80 54 16 49 14 58 28 53 23 26
7 24 60 10 67 53 69 32 23 2 66 12
7 34 40 48 21 3 57 43 6 18 27 80
7 45 20 3 65 21 61 17 12 69 66 27
7 67 62 78 70 57 68 46 9 2 72 39
7 77 41 34 32 75 72 20 64 78 33 25
7 6 21 72 76 11 75 38 73 27 64 33
7 17 1 27 37 28 80 49 12 67 59 36
That first number isn't very random — shortly after that sequence of tests, it changed from 7 to 8, but was equally non-random. An alternative
way of generating random numbers is:
static int getRandomNumber(int Min, int Max)
{
int rnd;
int range = (Max - Min + 1);
while ((rnd = rand()) > RAND_MAX - (RAND_MAX % range))
;
return (rnd % range) + Min;
}
This avoids the bias from that fact that 82 doesn't divide RAND_MAX exactly, which would weight the distribution of the lower numbers slightly higher than the upper numbers in the range 0..81. It also avoids the unexpectedly consistent first number, though the new first number is also semi-predictable when the tests are run at 1-second intervals.
Sample results:
48 33 28 78 14 2 81 13 23 75 38 40
45 42 74 1 11 68 17 33 78 49 23 80
42 51 38 3 5 52 35 56 54 23 59 41
39 60 2 8 36 53 79 30 72 75 62 37
36 69 45 10 78 20 71 17 6 53 54 30
33 78 9 15 75 7 40 61 27 36 70 68
30 5 55 17 69 73 25 63 37 1 21 71
27 14 19 66 57 43 1 13 3 65 71 21
24 26 62 63 41 61 68 28 67 20 74 17
21 35 26 57 28 79 47 44 2 52 60 77
Notice that the first number decreases by 3; the second seems to increase by 9; ugh — the randomness isn't all that good. It's well known that rand() is often not a high quality PRNG (pseudo-random number generator), but I'm a little surprised by this apparently systematic behaviour with seeds that differ by 1 each time.
On my Mac, when I changed srand() to srandom() and rand() to random(), I got better (as in, more unpredictable) results:
29 1 7 11 25 52 63 15 26 55 75 64
40 4 64 18 8 57 73 27 38 15 60 28
43 3 27 17 1 58 26 72 73 18 20 7
76 16 27 43 64 20 63 30 35 17 33 57
79 47 32 33 6 30 35 7 38 55 25 61
69 57 79 75 15 54 5 35 21 46 65 61
30 79 66 14 56 39 19 8 50 47 76 33
62 65 81 44 52 39 25 30 54 12 24 68
27 49 60 72 53 35 14 41 63 46 45 65
67 39 9 11 60 19 64 73 43 17 21 26
And the Mac man page for random() still suggests using arc4random() instead, but this is a lot better than plain rand(). What you find on other systems will depend on the facilities provided by the system — rand() may not be as awful as it seems to be on Mac. Basically, be cautious with your choice of PRNG — especially if you're going to use systematically generated seeds (such as the current time).
For the purpose you propose (generating a random sequence of numbers ranging from 0 through 81, where each item differs from the others), you will need a particular kind of random number generator (RNG), one that can generate all possible permutations of 82 items (expressed as 82!, or 82 factorial). However, only a limited selection of RNGs can do this. In particular the C rand() function's implementation is unspecified, so is not guaranteed to generate that many permutations.
A pseudorandom number generator (PRNG, a kind of RNG as used here) can't generate more random number sequences than its period. For 82! permutations, no PRNG with a period less than 82! can do this (the next highest power of 2 is 2408, meaning the generator needs to takes a seed at least 408 bits, or 51 bytes, long for it to possibly do so -- and 51 bytes is much bigger than srand can usually take). Alternatively, for this purpose, you would be well advised to use an RNG that generates "unpredictable" numbers, which neither the C language nor the C library includes as standard. See "Shuffling" and "Unpredictable RNGs" in my article on randomness for more information.
I'm trying to do a partial sort with a threads,
my current output it
27 12 21 48 15 28 82 69 35 91
13 82 33 35 46 5 35 28 87 95
0 10 20 22 23 30 52 80 86 96
3 8 42 53 67 70 70 71 75 79
5 8 8 18 41 43 70 79 86 88
10 51 56 60 65 84 87 91 94 99
23 25 38 39 40 44 51 56 69 75
20 21 25 29 29 38 66 71 73 96
33 50 9 6 13 27 97 21 70 22
3 4 6 6 7 15 34 59 63 70
As you can see I am getting it partially sorted I want my output to be this (no merging at the end)
12 15 21 27 28 35 48 69 82 91
5 13 28 33 35 35 46 82 87 95
0 10 20 22 23 30 52 80 86 96
3 8 42 53 67 70 70 71 75 79
5 8 8 18 41 43 70 79 86 88
10 51 56 60 65 84 87 91 94 99
23 25 38 39 40 44 51 56 69 75
20 21 25 29 29 38 66 71 73 96
6 9 13 21 22 27 33 50 70 97
3 4 6 6 7 15 34 59 63 70
I can get the right output if instead of using a struct I use &array[i] and manually input the length
This is the code I have so far:
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <pthread.h>
int cmpfunc(const void *a, const void *b) {
return (*(int*)a - *(int*)b);
}
struct values {
int *arrayptr;
int length;
};
void *thread_fn(void *a) {
struct values *start = a;
qsort(start->arrayptr, start->length, sizeof(int), cmpfunc);
return (void*)a;
}
int main(int argc, const char *argv[]) {
FILE *fp = fopen(argv[3], "r");
FILE *fp1 = fopen("numS1.dat", "w+");
//amount of threads
int threadAmount = atoi(argv[1]);
//size of input
int numberAmount = atoi(argv[2]);
//multidimensional array
int array[threadAmount][numberAmount / threadAmount];
for (int i = 0; i < threadAmount; i++)
for (int j = 0; j < numberAmount / threadAmount; j++)
fscanf(fp, "%d", &array[i][j]);
pthread_t threadid[threadAmount];
for (int i = 0; i < threadAmount; ++i) {
struct values a = { array[i], numberAmount / threadAmount };
pthread_create(&threadid[i], NULL, thread_fn, &a);
}
for (int i = 0; i < threadAmount; ++i)
pthread_join(threadid[i], NULL);
for (int i = 0; i < threadAmount; i++) {
if (i != 0)
fprintf(fp1, "\n");
for (int j = 0; j < numberAmount / threadAmount; j++)
fprintf(fp1 ,"%d ", array[i][j]);
}
return 0;
}
Do you know where I am going wrong?
I think its the struct but everything I see online does what I'm doing.
You are passing a pointer to automatic storage to newly created threads: the struct values object becomes invalid as soon as the calling scope is exited, thus it cannot be reliably accessed by the new thread. You should allocate the struct values and pass the pointer to the allocated object as a parameter to pthread_create:
for (int i = 0; i < threadAmount; ++i) {
struct values *a = malloc(sizeof(*a));
a->arrayptr = array[i];
a->length = numberAmount / threadAmount;
pthread_create(&threadid[i], NULL, thread_fn, a);
}
The structure can be freed by the thread function before exiting.
Notes:
the way you split the array into chunks only works if the length is a multiple of the number of threads.
the comparison function does not work for large int values, you should use this instead:
int cmpfunc(const void *a, const void *b) {
return (*(int*)b < *(int*)a) - (*(int*)a < *(int*)b);
}
I know that there is mistake in second for loop but I am not able to figure out. I think after if the continue will take it to to for loop if a%i ==0 and if a%i!=0 than it should print a which would be an prime number , but instead it is printing all the numbers from 2 to 300. Please help!!
The continue and break instructions both instruct the inner i loop. So whatever happens, your code prints every value of a in the outer loop.
#include <stdio.h>
int main(void) {
int a, i;
for (a=1; a<=300; a++) {
for (i=2; i<a; i++) { // changed from the clumsy i<=a-1
if (a % i == 0)
break; // end loop if i is a divisor
}
if (i == a) // if the loop completed
printf ("%d\t", a);
}
return 0;
}
Program output:
2 3 5 7 11 13 17 19 23 29
31 37 41 43 47 53 59 61 67 71
73 79 83 89 97 101 103 107 109 113
127 131 137 139 149 151 157 163 167 173
179 181 191 193 197 199 211 223 227 229
233 239 241 251 257 263 269 271 277 281
283 293
It's also a rather crude way to figure out primes, but first things first.
Better try this:
#include<stdio.h>
int main()
{
int i,j,isPrime;
for(i=2;i<300;i++)
{
isPrime = 1; //Firstly we assume that the number is prime;
for(j=2;j<i-1;j++) // you can also use i/2 or sqrt(i) for checking
{
if(i%j==0) //This condition only evaluates to true when j is factor of i
{
isPrime = 0;
break; //Now as we have a factor we are sure its not prime,So break the loop;
}
}
if(isPrime == 1) printf("%d\t",i);
}
return 0;
}
In your inner loop, you do either a break or a continue. But this merely breaks or continues the inner loop, and the printf will be executed irrespective of which is chosen. If you'd pasted the code as text, I might have fixed it for you!