13_pdfsam_lecture2

13_pdfsam_lecture2 - Loops Any loop can be written with a...

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Unformatted text preview: Loops Any loop can be written with a while, do-while, or for loop Usually one type of loop is more natural E.g. the following three are equivalent i=0; while(i<N) { ssprintf(%d\n, i); ssi++; } for(i=0; i<N; i++) { ssprintf(%d\n, i); } i=0; do { ssif(i < N) { ssprintf(%d\n, i); ssi++; ss} } while(i < N); Loops Any loop can be written with a while, do-while, or for loop Usually one type of loop is more natural E.g. the following three are equivalent int n; do { ssprintf(enter a number:); ssn = read_int(); } while(n <= 0); int n; printf(enter a number:); n = read_int(); while(n <= 0) { ssprintf(enter a number:); ssn = read_int(); } int n; printf(enter a number:); for(n = read_int(); n <= 0 ; n = read_int()){ ssprintf(enter a number:); } break and continue A break inside a loop causes the loop to terminate immediately int n = 10; while( 1 ) { ssif(n == 0) break; ssn--; } A continue statement causes the loop to immediately begin executing the next iteration int n; for(n=0; n < 10; n++) { ssif(n == 0) continue; ssprintf(%d\n, n); } Common pitfalls What do these code fragments do? int i; for(i=0; i<10; i++); ssprintf(%d\n, i); int i=1; while( i = 1 ) { ssprintf(%d\n, i); 11111 (innite loop) ssi = 3; } Reserved words in C We've already covered half of the language! break case char default else continue double extern goto long short struct union while oat if register unsigned sizeof switch static typedef void for int return enum do More on printf Syntax: printf(format_string, val1, val2, . . . ); format_string can include placeholders that specify how the arguments val1, val2, etc. should be formatted %c : format as a character %d : format as an integer %f : format as a oating-point number %% : print a % character int i = 90; float f = 3.0; printf(%d roads\n, 42); printf(i = %d%%, f = %f\n, i, f); 42 roads i = 90%, f = 3.000000 ...
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This note was uploaded on 01/10/2010 for the course CS 2022 at Cornell.

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13_pdfsam_lecture2 - Loops Any loop can be written with a...

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