String Input with multiple lines

To read 3 lines with the cumbersome scanf(), code needs to look for '$', '\n', and EOF. The rest of input is discardable.

int count = 0;
int line = 0;
while (line < 3) {
  scanf("%*[^$\n]");  // Scan for any amount of characters that are not $ nor \n,
                      // "*" implies - do not save. 
  char ch;
  if (scanf("%c", &ch) != 1) {  // Read next character.
    break;
  }
  if (ch == '$') count++;
  else line++;
}

printf("$ count %d\n", count);

As @chux suggested, reading with fgets provides a convenient way to protect from buffer overrun and without having to hard code field-width modifiers in scanf conversion specifiers.

Here, if all you need to do is count the number of '$' characters found in your input (regardless of how many lines), you can simply read ALL the input in fixed sized chunks of data. fgets does just that. It doesn't matter if you have one line, or one million lines of input. It also doesn't matter if your input lines are one-character or one million characters long. You can simply read each line and count the number of '$' found within each chunks of data read, keeping a count of the total found.

You can do this for any character. If you wanted to also count the number of line, you can simply check for '\n' characters and keep a total there as well. The only corner-case in counting lines with fgets is to insure you protect against a non-POSIX end-of-file (meaning a file with no '\n' as the final character). There are a couple of ways to handle this. Checking that the last character read was a '\n' is as good as any.

Putting the pieces together, and protecting against a non-POSIX eof, you could do something similar to the following, which simply reads all data available on stdin and outputs a final '$' and line count:

#include <stdio.h>

#define MAXC 100

int main (void) {

    char buf[MAXC] = "";  /* buffer to hold input in up to MAXC size chunks */
    size_t lines = 0, dollars = 0;  /* counters for lines and dollar chars */
    int i = 0;

    while (fgets (buf, MAXC, stdin))    /* read all data */
        for (i = 0; buf[i]; i++)        /* check each char in buf */
            if (buf[i] == '$')          /* if '$' found */
                dollars++;              /* increment dollars count */
            else if (buf[i] == '\n')    /* if '\n' found */
                lines++;                /* increment line count */

    if (i && buf[i-1] != '\n')          /* protect against non-POSIX eof */
        lines++;

    /* output results */
    printf ("input contained %zu lines and %zu '$' characters.\n", 
            lines, dollars); 

    return 0;
}

Look things over and let me know if you have further questions.

scanf("%[]s", &userInput);" is the one only i have discovered to take all 3 lines of input, BUT i can't break the input loop and continue with my program.

"%[]" is an invalid scanf() specifier. Anything may happen, it is undefined behavior, including taking all lines in and not returning.

The 's' in the format serves no purpose here - drop it.

Yes fgets() is best but let us abuse scanf() to read 3 lines and look for '$'.

char line[3][100] = {0};
//                 v--------- Consume all leading whitespace 
//                 | vv ----- limit input to 99 characters as scan() appends a \0
//                 | || v-v-- Look for "not \n" 
#define FMT_1LINE " %99[^\n]"

// Let the compiler concatenate the 3 formats into 1 string for scanf
int scan_count = scanf(FMT_1LINE FMT_1LINE FMT_1LINE, line[0], line[1], line[2]);
// Check return value
if (scan_count == 3) {
  // Successfully read 3 lines
  int count = 0;
  for (int line_index = 0; line_index < 3; line_index++) {
    char *s = line[line_index];
    while (*s) {  // no need for strlen(), just loop until the null character
      count += *s == '$';
      s++;
    }
  }
  printf("$ count %d\n", count);
}

You write:

scanf("%[]s", &userInput); //This takes input but doesnt leave input loop

but the comment is at best misleading. Your format string is malformed, so the behavior of the scanf call is undefined. An empty scan set (between the [] in the format) does not make sense, because the resulting field could never match anything. Therefore, a ] appearing immediately after the opening ] of the scan set is interpreted as a literal character not the ending delimiter. Your scan set is therefore unterminated.

Note, too, that %[ is its own field type, separate from %s. An 's' following the closing ] of the scan set is not part of such a field descriptor, but rather an ordinary character to match.

A trivial way to do this with scanf would be to read characters one at a time in a loop via a %c field. This is probably not what the exercise is looking for, and it's a hack to use scanf() instead of getchar() for this purpose, but perhaps it would serve:

int nl_count = 0;
int dollar_count = 0;

do {
    char c;
    int result = scanf("%c", &c);

    if (result != 1) {
        break;
    }
    switch (c) {
        case '\n':
            nl_count++;
            break;
        case '$':
            dollar_count++;
            break;
    }
} while (nl_count < 3);

I'm afraid it would be much more complicated to do it safely reading multiple characters at a time with a %[ field, and there is no safe way to read all three lines in one scanf call, unless you can rely on the input lines not to exceed a line length limit known to you.

int readMatrix() {

char userInput[100][3];    //Store user input
int j = 0, m = 0;

for(m = 0; m < 3; m++){
    scanf("%s", &userInput[j][m]); //This takes input (Ex: 22 *(enter)* 33$ *(enter)* 66$ *(enter)*
    j++; //increase the column
}



int i =0,count =0;
m = 0;
//Loop through the user input, if the character is '$', the integer count will be incremented
for (i = 0; i < 100; i++){
    for(m = 0; m < 3; m++){
        if (userInput[i][m] == '$'){
            count++;
        }
    }
}
printf("%d", count);
return 0;
}