2. Enter a pair of braces {}, and then all the steps are carried out in them, defining plastic variables n 1, n2, n3, n4 and character variable c..

3. Control the input and judgment of the string through the loop (and the loop needs to add a set of braces).

4. use if statement to judge the type of character if(c >；; = ' a ' & amp& ampc & lt= ' z ' | | c & gt= ' A ' & amp& ampc & lt= ' Z ')； n 1++； else if(c = = ' ')； n2++； else if(c & gt； = ' 0 ' & amp& ampc & lt= ' 9 ')n3++； elsen 4++； .

5. Output the result printf ("English letters %d, spaces %d, numbers %d, other characters %d", n 1, n2, n3, n4); .

6. Then save it all, compile it and run it to see the results.